Tocharian, also spelled Tokharian ( or ；Chinese: 吐火羅語), is an extinct branch of the Indo-European language family, known from manuscripts dating from the 6th to the 8th century AD found in oasis cities on the northern edge of the Tarim Basin (now part of Xinjiang in northwest China). The discovery of these languages in the early 20th century contradicted the formerly prevalent idea of an east–west division of Indo-European language family on the centum–satem isogloss, and contributed to re-invigorated study of the family. The term "Tocharian", based on an identification with the Bactrian Tokharoi of classical sources, is now generally considered a misnomer, but has become customary.