Elliot Sperling has argued in favor of a recent tendency by some authors writing in Chinese to revive the term Tubote () for modern use in place of Xizang, on the grounds that Tubote more clearly includes the entire Tibetan plateau rather than simply the Tibet Autonomous Region. The English word Tibet or Thibet dates back to the 18th century. Historical linguists generally agree that "Tibet" names in European languages are loanwords from Semitic or (; ), itself deriving from Turkic (plural of ), literally 'The Heights'. Language Linguists generally classify the Tibetan language as a Tibeto-Burman language of the Sino-Tibetan language family although the boundaries between 'Tibetan' and certain other Himalayan languages can be unclear. According to Matthew Kapstein:From the perspective of historical linguistics, Tibetan most closely resembles Burmese among the major languages of Asia. Grouping these two together with other apparently related languages spoken in the Himalayan lands, as well as in the highlands of Southeast Asia and the Sino-Tibetan frontier regions, linguists have generally concluded that there exists a Tibeto-Burman family of languages. More controversial is the theory that the Tibeto-Burman family is itself part of a larger language family, called Sino-Tibetan, and that through it Tibetan and Burmese are distant cousins of Chinese. The language has numerous regional dialects which are generally not mutually intelligible. It is employed throughout the Tibetan plateau and Bhutan and is also spoken in parts of Nepal and northern India, such as Sikkim. In general, the dialects of central Tibet (including Lhasa), Kham, Amdo and some smaller nearby areas are considered Tibetan dialects. Other forms, particularly Dzongkha, Sikkimese, Sherpa, and Ladakhi, are considered by their speakers, largely for political reasons, to be separate languages. However, if the latter group of Tibetan-type languages are included in the calculation, then 'greater Tibetan' is spoken by approximately 6 million people across the Tibetan Plateau. Tibetan is also spoken by approximately 150,000 exile speakers who have fled from modern-day Tibet to India and other countries. Although spoken Tibetan varies according to the region, the written language, based on Classical Tibetan, is consistent throughout. This is probably due to the long-standing influence of the Tibetan empire, whose rule embraced (and extended at times far beyond) the present Tibetan linguistic area, which runs from Gilgit Baltistan in the west to Yunnan and Sichuan in the east, and from north of Qinghai Lake south as far as Bhutan.