About the time of Vasubandhu there existed four schools of Indian Buddhism called Vaibhâshika, Sautrântika, Mâdhyamika and Yoga or Yogâcâra.[230] They were specially concerned with philosophy and apparently cut across the older division into eighteen sects, which at this period seem to have differed mainly on points of discipline. Though not of great practical importance, they long continued to play a certain part in controversial works both Buddhist and Brahmanic. The first two which were the older seem to have belonged to the Hinayana and the other two even more definitely to the Mahayana. I-Ching[231] is quite clear as to this. "There are but two kinds of the so-called Mahayana" he says, "first the Mâdhyamika, second the Yoga.... These two systems are perfectly in accordance with the noble doctrine. Can we say which of the two is right? Both equally conform to truth and lead us to Nirvana" and so on. But he does not say that the other two systems are also aspects of the truth. This is the more remarkable because he himself followed the Mûla-sarvâstivâdins. Apparently Sarvâstivâdin and Vaibhâshika were different names for the same school, the latter being applied to them because they identified themselves with the commentary (Vibhâshâ) already mentioned whereas the former and older designation came to be used chiefly with reference to their disciplinary rules. Also there were two groups of Sarvâstivâdins, those of Gandhara and those of Kashmir. The name of Vaibhâshika was applied chiefly to the latter who, if we may find a kernel of truth in legends which are certainly exaggerated, endeavoured to make Kashmir a holy land with a monopoly of the pure doctrine. Vasubandhu and Asanga appear to have broken up this isolation for they first preached the Vaibhâshika doctrines in a liberal and eclectic form outside Kashmir and then by a natural transition and development went over to the Mahayana. But the Vaibhâshikas did not disappear and were in existence even in the fourteenth century.[232] Their chief tenet was the real existence of external objects. In matters of doctrine they regarded their own Abhidharma as the highest authority.[233] They also held that Gotama had an ordinary human body and passed first into a preliminary form of Nirvana when he attained Buddhahood and secondly into complete Nirvana at his death. He was superhuman only in the sense that he had intuitive knowledge and no need to learn. Their contempt for sutras may have been due to the fact that many of them discountenance the Vaibhâshika views and also to a knowledge that new ones were continually being composed. I-Ching, who ends his work by asserting that all his statements are according to the Ârya-mûla-sarvâstivâda-nikâya and no other, gives an interesting summary of doctrine.