Asoka recognized proselytism by peaceful means as a state duty. The rock inscriptions record how he sent forth missionaries "to the utmost limits of the barbarian countries," to "intermingle among all unbelievers" for the spread of religion. They shall mix equally with Brahmans and beggars, with the dreaded and the despised, both within the kingdom "and in foreign countries, teaching better things." Conversion is to be effected by persuasion, not by the sword. This character of a proselytizing faith which wins its victories by peaceful means has remained a prominent feature of Buddhism to the present day. Asoka, however, not only took measures to spread the religion; he also endeavoured to secure its orthodoxy. He collected the body of doctrine into an authoritative version, in the Magadhi language or dialect of his central kingdom in Behar--a version which for two thousand years has formed the canon (_pitakas_) of the southern Buddhists. The fourth and last of the great councils was held in Kashmir under the Kushan king Kanishka (see below). This council, which consisted of five hundred members, compiled three commentaries on the Buddhist faith. These commentaries supplied in part materials for the Tibetan or northern canon, drawn up at a subsequent period. The northern canon, or, as the Chinese proudly call it, the "greater vehicle of the law," includes many later corruptions or developments of the Indian faith as originally embodied by Asoka in the "lesser vehicle," or canon of the southern Buddhists. The Kanishka commentaries were written in the Sanskrit language, perhaps because the Kashmir and northern priests who formed his council belonged to isolated Aryan colonies, which had been little influenced by the growth of the Indian vernacular dialects. In this way Kanishka and his Kashmir council became in some degree to the northern or Tibetan Buddhists what Asoka and his council had been to the Buddhists of Ceylon and the south.[3] Buddhism and Brahmanism.