Tibet, a historical plateau region in Central Asia, is today mostly under the sovereignty of the People's Republic of China and administered as the Tibet Autonomous Region. However, the term "Tibet" is subject to many definitions and controversy over its function and territorial claims.
Names for "Tibet" range from the Standard Tibetan endonym Bod to exonyms such as Mandarin Tǔbō or Tǔfān 吐蕃 and English language Tibet.
The Standard or Central Tibetan endonym Bod "Tibet" (Tibetan: བོད་) is pronounced [pʰøʔ], transliterated Bhö or Phö.
Rolf Stein explains,
The name Tibetans give their country, Bod (now pronounced Pö in the Central dialect, as we have seen), was closely rendered and preserved by their Indian neighbours to the south, as Bhoṭa, Bhauṭa or Bauṭa. It has even been suggested that this name is to be found in Ptolemy and the Periplus Maris Erythraei, a first-century Greek narrative, where the river Bautisos and a people called the Bautai are mentioned in connexion with a region of Central Asia. But we have no knowledge of the existence of Tibetans at that time.
Christopher Beckwith agrees that Ptolemy's geographic reference to the "Bautai – i.e., the "Bauts"" was "the first mention in either Western or Eastern historical sources of the native ethnonym of Tibet". He compares the 4th-century historian Ammianus Marcellinus describing the Bautai living "on the slopes of high mountains to the south" of Serica with contemporaneous Chinese sources recording a Qiang people called the Fa , anciently "pronounced something like Puat" and "undoubtedly intended to represent Baut, the name that became pronounced by seventh-century Tibetans as Bod (and now, in the modern Lhasa dialect, rather like the French peu)." Bod originally named the Central Tibetan region Ü-Tsang or Dbus-gtsang.