Tannu Uriankhai

Tannu Uriankhai (Tuvan: Таңды Урянхай, [taŋˈdɤ urʲanˈχaj]; Mongolian: Тагна Урианхай, romanized: Tagna Urianhai, [ˈtʰaɢəɴ ʊrʲæŋˈχæɪ̯]; simplified Chinese: 唐努乌梁海; traditional Chinese: 唐努烏梁海; pinyin: Tángnǔ Wūliánghǎi) was a historical region of the Mongol Empire, its principal successor, the Yuan dynasty, and later the Qing dynasty. The territory of Tannu Uriankhai largely corresponds to the modern-day Tuva Republic of the Russian Federation, neighboring areas in Russia, and a small part of the modern state of Mongolia.

Tannu designates the Tannu-ola Mountains in the region, and Uriankhai was the Mongolian name for the Tuvans (and accordingly their realm), which meant "the people living in the woods" (Chinese: 林中百姓; pinyin: Línzhōng Bǎixìng).

After Mongolia (Outer Mongolia) declared independence from the Qing dynasty and the Republic of China in the early 20th century, the region of Tannu Uriankhai increasingly came under Russian influence and finally became an independent communist state, the Tuvan People's Republic, which was annexed by the Soviet Union in 1944.

Sovereignty over the area has not been officially renounced by the Republic of China since 1949. However, the Mainland Affairs Council issued a statement saying that "Outer Mongolia has never been part of its constitutionally claimed territory."

The 2001 Sino-Russian Treaty of Friendship states that the People's Republic of China (PRC), which controls Mainland China, and the Russian Federation, which controls Tuva, "have no remaining territorial claims". The PRC has official contacts with Tuva and regards it as part of Russia.