The lanterns cast a warm, golden glow over the side hall in Gong'an. Zhang Zhongjing sat at a low table, polishing herbs with steady, practiced hands. Zhuge Liang fanned himself slowly, his gaze distant and thoughtful. Pang Tong and Fa Zheng leaned casually against a wooden pillar, looking like two men who had just realized the rulebook had been rewritten overnight.
Compared to Li Shimin's court, who had piles of old records to cross-check everything the Light Screen showed them, Liu Bei's ministers were playing a completely different game.
They could only stare at one another. Big eyes meeting even bigger eyes. Some of the sharpest minds of the age, and collectively they had the brainpower of a confused goldfish.
"Did anyone here actually understand what just happened?" Pang Tong asked, breaking the stillness.
"I understood the part where we are all still alive," Fa Zheng said. "Everything after that is negotiable."
Because if the Light Screen was right, Five-Stone Powder really blew up during the Jin Dynasty. And right now? The Great Han was still standing tall, thank you very much.
So when it came to just how deadly this powder really was, all they could do was piece together hints from whatever scattered clues the future happened to let slip.
Doctor Zhang confirmed one thing straight away though. Five-Stone Powder did originate during the Han. No hesitation there.
But because the Light Screen had warned them about the dangers early on, everyone under Liu Bei's banner had already steered well clear of the stuff. Even Liu Zhang, sitting over in Jiangling doing nothing but enjoying the good life, never touched it.
Which made it all the harder to wrap their heads around how something like this could ruin a whole country and wreck entire families.
"Doctor Zhang, have you ever seen a poppy?"
Zhuge Liang cared more about this specific plant than anything else the screen had mentioned. He turned straight to Zhang Zhongjing and asked.
Zhang Zhongjing stroked his beard and sank into thought. The weight on his shoulders felt like it just got a few jin heavier.
"I have not. Or perhaps the names in old and newer texts simply differ for the same plant."
"That would not surprise me," Fa Zheng said. "A single herb may bear several names, depending on the physician, the region, or the text."
That made the most sense. The Silk Road had been linking East and West for ages. If this stuff really worked the way they said, surely someone would have shipped it to the Han ages ago to make a massive profit.
"So why haven't we seen it?" Pang Tong asked.
"Maybe we have," Zhuge Liang said. "And we simply do not recognize it."
He nodded slowly, still turning it over in his head. He exchanged a look with Pang Tong and Fa Zheng. Both men's eyes were gleaming with that same sharp, probing curiosity.
Between the three of them, they could tell the future was definitely holding back plenty of details.
The different names for poppy and opium products. Exactly what addiction actually looked like. All of it was being kept vague on purpose.
"They are treating it like we treat the Daoist sects," Pang Tong said. "When something harms people, you warn them. You do not hand out the details."
"Smart," Fa Zheng muttered. "If they told us exactly how to prepare it, some fool would try it within the week."
"And that fool would probably be you," Pang Tong said.
Fa Zheng gave him a flat look. "If I were foolish enough to experiment with an unknown poison, I would at least have the courtesy to do it somewhere far away from you."
And looking at the bigger picture of history ahead, contact between the Han and the West was going to happen. There was no avoiding it.
"If we want to win every battle, we have to know our enemy," Zhuge Liang said. "We should not begin by asking how it is abused. First determine why physicians value it. If it has legitimate medicinal uses, banning it blindly may only drive those uses underground."
But right now, the future hadn't said nearly enough. Eventually they'd probably have to rely on merchants traveling the Silk Road to gather what they could.
"And every part of this needs to be discussed carefully with Lord Liu first," Zhuge Liang added. "And kept strictly confidential."
That sense of crisis Pang Tong and Fa Zheng had been feeling? It just got sharper.
To be honest, it had never really gone away.
Everything the future had shown them had changed how they understood running a state and caring for the people. Mathematics was essential. Engineering carried terrifying power. Literature still mattered. And now it turned out medicine alone could bring down a nation.
"First you buried me in tax records," Pang Tong muttered. "And now you have handed me poison to investigate. At this rate, Kongming, I expect the next revelation to concern the proper storage of pickled vegetables."
"Do not laugh. Poorly stored food kills more people than most armies," Fa Zheng said.
If you wanted to secure the state above and protect the people below, the knowledge you needed was more complicated than ever before.
And every single time, Zhuge Liang got there first. Take Doctor Zhang, for example. Everyone knew his skill was divine. But the person closest to him, the one working most closely alongside him? Still Zhuge Liang.
Pang Tong sighed. He was starting to think compiling something like that future encyclopedia they'd heard about might not be such a bad idea after all.
At the very least, after reading through something that big, even if you didn't master everything, you'd still pick up a hundred useful things. And that alone would be enough to give you a head start in governing well.
"Or," Fa Zheng said, "you could just admit Zhuge Liang will read it faster and explain it to us later."
Pang Tong shot him a look. "I have my pride."
"Pride does not write books."
"It also does not ask for help."
"Which is why you suffer."
Zhuge Liang continued fanning himself. "You may continue arguing after you finish the report."
[Lightscreen]
[Five-Stone Powder is actually a pretty fascinating substance in its own right.
For example, during the Southern Dynasties, the famous Ge Hong recorded the ingredients as cinnabar, realgar, white alum, azurite, and lodestone.
The Sui Dynasty's renowned physician Chao Yuanfang left behind a different record: stalactite, sulfur, white quartz, purple quartz, and red halloysite.
As for He Yan, the man who kicked off the entire Five-Stone Powder trend in the first place, his specific formula is completely lost to history.
Additionally, He Yan was reportedly the legitimate grandson of Grand General He Jin. After the Gaoping Tombs Incident, he was falsely accused and executed by Sima Yi, the future Emperor Xuan of Jin, and his entire clan was exterminated to the third degree.
From this angle, the Gaoping Tombs Incident truly was a pivotal event connecting the late Han to the Jin.
The great plague of the 22nd year of Jian'an completely transformed Cao Pi's personality. The extravagant lifestyle he pioneered gradually spread through the entire aristocratic class.
He Yan took that foundation and ran with it. Together with Xiahou Xuan and Wang Bi, he raced to perfect the art of Pure Conversation, setting the cultural tone for an entire generation and founding what we now call Wei-Jin Metaphysics.
Yuan Hong of the Eastern Jin wrote Biographies of Famous Scholars and called these three the Zhengshi Scholars, which tells you just how towering their reputation was at the time.
When the number one celebrity of the era personally endorses a product, the effect is roughly the same as Li Bai writing poems about tea and wine during the Tang Dynasty. The sales numbers can only be described as absolutely insane.
And because the plague never stopped, and cold-damage illness made people's bodies freeze, and ancient methods of staying warm were limited to say the least, Five-Stone Powder, which stimulated internal heat, became wildly popular.
The hallucinogenic side effect made users feel like they were floating among the immortals. People who tried it could not stop singing its praises.
But if consumed long-term, the damage caused by Five-Stone Powder was far more violent than any opium product. Beyond creating dependency, records of death and disability from Five-Stone Powder never once stopped throughout the Two Jin and Northern-Southern Dynasties.
By the Tang Dynasty, Sun Simiao also invested significant effort into studying Five-Stone Powder and issued a stark warning.
Five-Stone Powder is a fierce and deadly poison. I would rather eat wild hemlock than consume Five-Stone Powder. If you encounter this formula, burn it immediately. Do not let it become a plague upon the living.
But the disappearance of Five-Stone Powder could not rely on a single medical KOL like Sun Simiao making a recommendation. There were many other complex factors at play.
The biggest factor was something far more powerful than any emperor or general: the climate itself had begun to change.
After the long cold period of the Two Jin and Northern and Southern Dynasties, China gradually entered a warmer phase around the Sui and Tang era. The average temperature during the Tang Dynasty was about 1.5 degrees Celsius higher than our current average, and roughly 2 degrees higher than the late Han.
That may not sound like much.
But when you are talking about the difference between a failed harvest and a full granary, 2 degrees can reshape the fate of nations.
Let me show you a chart, because this is one of those cases where the relationship becomes much easier to see when everything is placed side by side.
At the center of the chart is the temperature variation index, which gives us the most straightforward picture of when China was moving through warmer and colder phases. Above it are three other indicators that help us see what those climatic changes meant on the ground: the latitude of the agricultural-pastoral transition zone, the rice price index across different historical periods, and the number of recorded wars.
Once you look at all four together, an interesting pattern begins to emerge.
As the great cold of the Two Jin and Northern and Southern Dynasties gradually receded, the agricultural-pastoral transition zone began shifting northward and northwestward. This meant that regions which had previously been too cold or marginal for intensive farming could become increasingly suitable for agriculture. During warmer phases, the agricultural frontier could therefore expand, while during colder periods it tended to retreat.
That might sound like a relatively minor geographical change until you remember what agriculture meant to an ancient state.
For a modern person, a warmer year might mean turning the air conditioner up a little more. For an ancient farmer, however, a warmer and more favorable growing season could determine whether a field produced enough grain to feed a household. Multiply that across millions of hectares and suddenly a change in climate becomes an economic and political event.
More productive farmland meant more grain, and more grain gave the population a greater margin of safety. It could help stabilize food supplies, reduce pressure on prices, and provide governments with larger agricultural surpluses that could be taxed, stored, transported, and eventually converted into military power.
This is where the rice-price line on the chart becomes particularly interesting. Food prices were one of the most immediate ways ordinary people experienced changes in agricultural conditions. When harvests were reliable, markets had a much easier time staying supplied. When droughts, floods, or other forms of climatic stress damaged production, the consequences could spread rapidly through the economy, pushing food prices upward and placing enormous pressure on households.
And once food became expensive, the problem was no longer simply agricultural.
It became political.
The same applies to warfare. Some of the largest conflicts in ancient China were connected to the agricultural-pastoral frontier, where farming states and pastoral societies competed over land, resources, and political influence. Climate did not mechanically cause every war, because human beings have always been perfectly capable of finding reasons to fight without any assistance from the weather, but it could alter the conditions in which those conflicts took place.
When colder conditions reduced agricultural productivity and placed greater pressure on pastoral lands, migration and competition for resources could intensify. When conditions became more favorable, agricultural societies could expand their productive frontier and states could support larger populations and stronger institutions.
So the chart should not be read as saying that temperature controls history like some invisible emperor sitting in the heavens.
It is showing something more subtle.
Climate changes the difficulty level.
A capable government operating during favorable climatic conditions has more room to experiment, expand, tax, build infrastructure, and maintain armies. The same government operating through repeated harvest failures has far less room for mistakes, because every bad harvest can push food prices higher, reduce tax revenues, increase migration, and create new opportunities for rebellion or external pressure.
The colder centuries had their own peculiar ways of coping with discomfort as well. During the Wei and Jin period, the infamous Wushi San, or Five-Mineral Powder, became popular among parts of the elite. The substance was associated with stimulating heat and producing unusual physical sensations, and its use became deeply intertwined with the culture and medical practices of the period.
So, yes, one could make the joke that once China started warming up, perhaps nobody needed to swallow Five-Mineral Powder just to feel warm anymore.
Unfortunately, history is not quite that cooperative.
The decline of Wushi San had far more to do with changing medical practices, elite culture, and political circumstances than with the temperature simply becoming more comfortable. The warming climate belongs in the larger story of the period, but it should not be blamed for every cultural change that happened to occur at the same time.
What the climate did help provide was a more favorable agricultural environment, and that mattered enormously because China was simultaneously emerging from centuries of political fragmentation.
In 589, Emperor Wen of Sui destroyed the Chen dynasty and reunited China, bringing an end to nearly 3 centuries of division between the north and south. He then began rebuilding the machinery of a unified empire, strengthening the administration, reorganizing taxation, encouraging agricultural recovery, accumulating grain reserves, and restoring a political order in which Confucian learning once again became an important part of government.
The timing was remarkable because political reunification and environmental recovery could reinforce one another.
A more favorable climate could support agricultural expansion, agricultural expansion could support population growth, population growth could provide a larger tax base, and a stronger tax base could give the newly reunified state the resources needed to maintain armies, construct infrastructure, and govern a much larger territory.
That does not mean the Sui and Tang dynasties succeeded simply because the weather was nice. Political institutions, military organization, economic policy, technological development, and the decisions of individual rulers still mattered enormously.
But climate could determine how much room those institutions had to work.
And that is why the chart is so useful.
When the temperature rises, the agricultural frontier begins to move with it. Food production and prices respond to the changing conditions, while the pressures surrounding the farming-pastoral frontier and warfare shift as well. None of these lines tells the whole story by itself, but together they reveal something that is easy to miss when looking at individual emperors and battles.
The rise of the Sui and Tang was not happening in an empty environment.
China was emerging from a colder and more unstable period into a climate that was, for a time, considerably more favorable to agriculture. The state was rebuilding at almost exactly the same time, and the combination gave the new empire an unusually strong foundation on which to grow.
The Tang golden age was therefore not created by climate alone, but the climate helped provide the raw material from which that golden age could be built.
The emperors still had to govern it.
The farmers still had to harvest it.
And the state still had to make sure it did not somehow spend all of it.
Furthermore, the retreat of the cold stripped cold-damage plague of the soil it needed to take root. After all, the climate was already hot enough. Nobody needed Five-Stone Powder to stimulate body heat anymore.
Under the watchful gaze of Confucian culture, the Wei-Jin scholar habit of streaking at the drop of a hat looked extremely inappropriate.
Moreover, after the Tang Dynasty, cotton arrived in China and began to shine. Cotton fabric was cheaper to produce and provided better insulation.
With all these factors stacking together, large-scale cold-damage plagues like those of the late Han lost nearly all the conditions they needed to take root. The popular use of Five-Stone Powder among common people came to a permanent stop.
However, Five-Stone Powder did not completely vanish from the aristocratic class. The Song Dynasty, building on Tang research into stalactite compounds, modified the Five-Stone Powder formula to reduce its toxicity.
Then the Ming Dynasty decided to go big. On top of the existing formula, they added male silkworm moths, urine powder, menstrual blood from virgin girls, and red lead, creating the famous royal aphrodisiac known as the Red Pill.
And if you connect this to the inexplicably short lifespans of Ming Dynasty emperors, well, the effectiveness of the Red Pill is... let us just say it speaks for itself.]
The hall in Chang'an went very still after that final line.
Liu Bei was the first to speak, and his voice carried the careful tone of a man choosing each word like he was defusing a bomb.
"Let me make certain I have understood this correctly. The emperors of the Ming took pills containing moth parts, powdered urine, menstrual blood, and red lead, and those same emperors repeatedly died young. And the Light Screen would have us believe that this was no coincidence."
Zhuge Liang pinched the bridge of his nose. "My lord, I believe the Light Screen is suggesting it was very much not a coincidence."
Zhang Fei, who had been listening with the expression of a man watching someone eat a live scorpion, finally exploded.
"Wait. Wait wait wait. They put WHAT in the pill? Urine powder? Gods above. If a man wishes to drink his own piss, let him do it from a cup. Why grind it into a pill and pretend heaven prescribed it?"
Guan Yu, who rarely engaged in these discussions, set down his tea with deliberate calm.
"The real question is why no doctor stopped them. Any doctor with half a brain would know red lead is toxic."
Fa Zheng, sitting in the corner with his arms crossed, gave a dry laugh.
"Yide, you are assuming the doctors had the power to say no to an emperor who wanted to perform better in bed. I assure you, that conversation does not end well for the doctor."
Pang Tong nodded grimly. "If the emperor insists on hearing that the pill will make him stronger, then the doctor who tells him otherwise is unlikely to keep his position for long. Someone else will eventually give the emperor the answer he wants. And once that happens, the doctor is no longer treating a patient. He is serving the emperor's desire and calling it medicine."
Liu Bei shook his head slowly, processing.
"So the Five-Stone Powder destroyed the Wei-Jin scholars from the inside. And the Red Pill destroyed the Ming emperors from the inside. Different dynasties. Different formulas. Same result."
Zhuge Liang's brush paused over his notes. "Same result, my lord. The ruling class poisons itself while believing it is being nourished. And by the time anyone notices, the damage is structural."
Zhang Zhongjing, who had been still through most of this exchange, finally spoke. His voice was low and steady, but there was a hardness underneath it that made everyone in the room sit up straighter.
"I will say this once, and I will say it clearly. Red lead is a poison. Menstrual blood has no medicinal value in this context. Urine powder contributes nothing. The silkworm moth adds nothing. The only active ingredient in that entire formula is the poison. Everything else is theater."
He paused, letting the words settle.
"If the doctor knew the substance was poisonous and still prescribed it as a medicine, then he was no longer merely mistaken. He was gambling with the emperor's life."
The room stayed still for a long moment after that.
Then Jian Yong, who had been scribbling notes in the back, raised his hand like a student asking permission to speak.
"Quick question. The Light Screen mentioned that climate warming killed Five-Stone Powder more effectively than any doctor. Does that mean if the climate cools again, the powder comes back?"
Every head in the room turned toward Zhang Zhongjing.
The old doctor closed his eyes. Opened them. Closed them again.
"If the cold returns and no one has preserved the knowledge of why the powder is dangerous, then yes. It comes back. And it comes back exactly as vicious as before."
Liu Bei stood up. The motion was sudden enough that his chair scraped against the floor.
"Then we write it down. All of it. The formula. The symptoms. The progression. The treatment. The warning. We write it down in language so clear that even a village doctor 300 years from now can read it and know exactly what he is looking at."
He turned to Zhang Zhongjing.
"Doctor Zhang. I am commissioning you to write this section of the Treatise. Not as a footnote. Not as an aside. As a full chapter with its own heading. Let every doctor who reads your work for the next thousand years understand what Five-Stone Powder does. Let them understand what opium does. Let them understand that the cure and the poison can wear the same face."
Zhang Zhongjing bowed his head. Not in submission. In acceptance.
"This old man will write it."
Zhuge Liang resumed his brushwork, adding a new column to his notes. At the top, he wrote two characters: Climate. Below it, he wrote: Medicine. Below that: Governance. Then he drew a line connecting all three.
Because that was the lesson the Light Screen had been teaching them from the very beginning. Everything was connected. The temperature of the air decided whether a plague took root. Whether a plague took root decided whether a drug became popular. Whether a drug became popular decided whether a generation of scholars lived or died. Whether a generation of scholars lived or died decided whether a dynasty lasted 2 centuries or 2 decades.
And somewhere in the middle of all that, a single emperor decided to swallow a pill made from moth parts and red lead because he wanted to impress his concubines.
History was not a river. It was a house of cards, and every card was made of human choices.
Pang Tong leaned over to Fa Zheng and whispered.
"Do you think the future generations will look back at us the same way? Will they say the Han fell because of climate, or because of bad decisions?"
Fa Zheng did not whisper back. He answered at full volume.
"They will blame whichever one makes the better story. The climate may have weakened the Han, but men still had to decide what to do about it."