Tibet is the traditional center of Tibetan Buddhism, a distinctive form of Vajrayana, which is also related to the Shingon Buddhist tradition in Japan. Tibetan Buddhism is not only practiced in Tibet; it is also the prevalent religion in Mongolia and largely practiced by the Buryat people of Southern Siberia. Tibet is also home to the original spiritual tradition called Bön (also spelled Bon). Various dialects of the Tibetan language are spoken across the country. Tibetan is written in Tibetan script.

In Tibetan cities, there are also small communities of Muslims, known as Kachee (Kache), who trace their origin to immigrants from three main regions: Kashmir (Kachee Yul in ancient Tibetan), Ladakh and the Central Asian Turkic countries. Islamic influence in Tibet also came from Persia. After the invasion of Tibet in 1959 a group of Tibetan Muslims made a case for Indian nationality based on their historic roots to Kashmir and the Indian government declared all Tibetan Muslims Indian citizens later on that year. [12] There is also a well established Chinese Muslim community (gya kachee), which traces its ancestry back to the Hui ethnic group of China. It is said that Muslim migrants from Kashmir and Ladakh first entered Tibet around the 12th century. Marriages and social interaction gradually led to an increase in the population until a sizable community grew up around Lhasa.