The story of steamed buns (包子, b1ozi) can purportedly be traced back to the Three Kingdoms era (220 – 280), when Zhuge Liang, chancellor of the Shu state, led his army against Nanman (literally “southern barbarian”) forces and took back a load of captives. When a river blocked their route home, a local warlord suggested throwing 49 Nanman heads into the water as a sacrifice. Zhuge apparently balked at this grisly proposal, so ordered his troops to sacrifice some livestock and use the meat to fill some head-sized buns. The river was seemingly becalmed by the offer and buns became a thing— mantou (蛮头) comes from “蛮” (barbarian) and “头” (head) During the Song dynasty, baozi or bao came to mean filled buns, while mantou specifically referred to regular buns, with “蛮头” evolving into the homophone “馒头.”
Today’s baozi is no longer the size of a decapitated head (and is usually a more appetizing proposition), but instead come in a variety of competing forms, aside from xiaolongbao.