Why was Xinjiang once called the Western Regions?

For centuries, the region now known as Xinjiang was referred to by the Chinese as Xiyu, which translates to "Western Regions". This designation was used to describe the area located to the west of the Chinese heartland, particularly the territories beyond the Great Wall and the Jade Gate (Dunhuang) that were explored and influenced by the Han dynasty during their expansion into Central Asia.12

The name "Western Regions" reflected the area's geographic position relative to the center of Chinese imperial power at the time. It remained the standard term for the region until the 18th century, when it was annexed by the Qing (Manchu) dynasty and renamed Xinjiang, meaning "New Borders".1