The main language spoken in Tibet is the Tibetan language. Apart from the Tibetan language languages like English is also used in the tourism business and other languages like Hindi and Nepalese are spoken by the Indian and Nepalese merchants. Tibetan language is also spoken in Nepal (in the Nepal-Tibet border areas), Bhutan and India (mainly in Sikkim). This language is classified by the linguists as the member of Tibeto-Burman subgroup of the Sino-Tibetan languages but its origin goes back to the mother language Sanskrit.
Written in a very conservative yet beautifully syllabary script, the writing system of Tibetan language follows the ancient Sanskrit language writing style. Development of the present Tibetan language dates back to the 9 th century. It was developed as a means of translating sacred Buddhist texts that were being brought from India to Tibet. If you go a little deeper study of the Tibetan language you will find that the writing style of the Tibetan language matches to the writing styles and pronunciation of the languages from the 7 th century. There are thousands of books and dharma texts today which were able to survive the Chinese invasion. The languages used in these texts are called Classical Tibetan. Among these huge numbers of texts it’s said those only 1 /1000th portions of the texts are translated to the date in western or any other languages. The Tibetan language spoken today is called Colloquial language by the western Tibetan scholars. Colloquial language is a language used in the 7th -9th century that has many similarities with the modern Tibetan language but there are many distinct differences too. Tibetan language has four major Dialects and people from widely separated regions sometime encounter difficulties communicating with each other. The Tibetan language spoken around the capital, Lhasa is considered the standard today. There is another form of language found in Tibet in writing called “Modern Literary Tibetan”.
Here are few books and tutorials if you are interested in learning the Tibetan language: