Initial identification of a distinct language occurred through study of one of the Buddhist āgamas, the Dīrghāgama, which had been translated into Chinese by Buddhayaśas () and Zhu Fonian ().
The now dominant hypothesis on the propagation of Buddhism in Central Asia goes back to 1932 when E. Waldschmidt remarked that the names quoted in the Chinese Dīrghāgama (T.