Tuyuhun

State · 287–665 CE · at its largest around 602 CE

Kingdom founded by a Xianbei group in the Qinghai region of western China, controlling trade routes until it was conquered by the Tibetan Empire.

On its lands while it lasted

Mogao Caves (c. 366 CE): Buddhist cave temples near Dunhuang created from the 4th to 14th centuries, with thousands of square metres of murals.
Zhangye (c. 397 CE): Capital of Northern Liang (397–439).