Tibet
The modern Standard Chinese exonym for the ethnic Tibetan region is Zangqu (Chinese: Cang Qu ; pinyin: Zangqu), which derives by metonymy from the Tsang region around Shigatse plus the addition of a Chinese suffix, Qu  qu, which means "area, district, region, ward". Tibetan people, language, and culture, regardless of where they are from, are referred to as Zang (Chinese: Cang ; pinyin: Zang) although the geographical term Xizang is often limited to the Tibet Autonomous Region. The term Xizang was coined during the Qing dynasty in the reign of the Jiaqing Emperor (1796-1820) through the addition of a prefix meaning "west" (Xi  xi) to Zang.
How is the ethnic Tibetan region referred to as a modern Standard Chinese exonym?
Zangqu
The modern Standard Chinese exonym for the ethnic Tibetan region is Zangqu (Chinese: Cang Qu ; pinyin: Zangqu), which derives by metonymy from the Tsang region around Shigatse plus the addition of a Chinese suffix, Qu  qu, which means "area, district, region, ward".
the ethnic Tibetan region