The Indo-European language of the Tocharian people living in the Tarim River until about 1000 AD. It is comprised of an eastern dialect (Tocharian A), from the area of Turfan, and a western dialect (Tocharian B), chiefly from the region of Kucha but also from the Turfan area. Tocharian is the easternmost Indo-European language. The earliest known record is from the 7th century AD.

Tocharian was written in a northern Indian syllabary known as Brahmi, which was also used in writing Sanskrit manuscripts from the same area.

Tocharian forms an independent branch of the Indo-European language family not closely related to other neighbouring Indo-European languages, such as the Indo-Aryan and Iranian. Rather, Tocharian shows a closer affinity with the Indo-European languages of the northwest. The vocabulary of the language shows the influence of Iranian and, later, Sanskrit. Chinese had little influence.