The Han–Xiongnu War, also known as the Sino–Xiongnu War, was a series of military conflicts fought over two centuries between the Chinese Han Empire and the nomadic Xiongnu confederation, although extended conflicts can be traced back as early as 200 BC and ahead as late as 188 AD.

The Protectorate of the Western Regions (simplified Chinese: 西域都护府; traditional Chinese: 西域都護府; pinyin: Xīyù Dūhù Fǔ; Wade–Giles: Hsi1-yü4 Tu1-hu4 Fu3) was an imperial administration (a protectorate) situated in the Western Regions administered by Han dynasty China and its successors on and off from 59 or 60 BCE until the end of the Sixteen Kingdoms period in 439 AD. The "Western Regions" refers to areas west of Yumen Pass, especially the Tarim Basin in southern Xinjiang. These areas would later be termed Altishahr (southern Xinjiang, excluding Dzungaria) by Turkic-speaking peoples. The term "western regions" was also used by the Chinese more generally to refer to Central Asia.