The Han Dynasty doesn't really care about allies or not. Except when fighting the Huns back then, the Han Dynasty considered drawing allies, but across the entire Eurasian continent, those they could find either gave ambiguous responses or treated Han envoys with good food and drink, and claimed to know nothing about what the Han proposed.
In the end, the Martial Emperor waved his hand in frustration, saying, "Don't tell me I can't deal with the Huns without allies?"
After that, there wasn't much more to say. The Han Dynasty, for hundreds of years, didn't have any allies. After all, it became clear that allies between countries were entirely unreliable, only strength was reliable. So later, the Han Dynasty didn't form alliances or friendly states with any country.
They all became younger brothers, paying tribute. We don't need allies; we can defeat our enemies alone and take all the benefits ourselves.
