Kuchean language

Kuchean (also known as Tocharian B or West Tocharian) was a Western member of the Tocharian branch of Indo-European languages, extinct from the ninth century. Once spoken in the Tarim Basin in Central Asia, Tocharian B shows an internal chronological development; three linguistic stages have been detected. The oldest stage is attested only in Kucha. There is also the middle ('classicalʼ), and the late stage.

Nomenclature
According to Peyrot, the self-designation for the language was kuśi 'Kuča'. In scholarly works, it is known as Tocharian B, sometimes referred to as West Tocharian or Kuchean.

Overview
According to scholar Michael Peyrot, Tocharian B is dated between the 5th and 10th centuries AD, and was spread from Kuča to Yānqi and Turfan. Paul Widmer, following Tamai's and Adams's studies, situates Tocharian B roughly between 400 and 1200, its oldest layer dating from ca. 400 to 600, around "Kucha and environs".

Documentation
According to J. H. W. Penney, Tocharian B is reported to be documented as Buddhist religious literature, and as secular material "pertaining to everyday life".