The Mahayana grows out of the Hinayana and in many respects the Hinayana passes into it and is preserved unchanged. It is true that in reading the Lotus we wonder how this marvellous cosmic vision can represent itself as the teaching of Gotama, but the Buddhacarita of Asvaghosha, though embellished with literary mythology, hardly advances in doctrine beyond the Pali sutras describing the marvels of the Buddha’s nativity[174] and the greater part of Nagarjuna’s Friendly Epistle, which purports to contain an epitome of the faith, is in phraseology as well as thought perfectly in harmony with the Pali Canon. Whence comes this difference of tone in works accepted by the same school? One difficulty of the historian who essays to account for the later phases of Buddhism is to apportion duly the influence of Indian and foreign elements. On the one hand, the Mahayana, whether we call it a development or perversion, is a product of Indian thought. To explain its trinities, its saviours, its doctrine of self sacrifice it is not necessary to seek abroad. New schools, anxious to claim continuity and antiquity, gladly retained as much of the old doctrine as they could. But on the other hand, Indian Buddhism came into contact with foreign, especially Iranian, ideas and undoubtedly assimilated some of them. From time to time I have drawn attention to such cases in this work, but as a rule the foreign ideas are so thoroughly mastered and indianized that they cease to be obvious. They merely open up to Indian thought a new path wherein it can move in its own way.
In the period following Asoka’s death Buddhism suffered a temporary eclipse. Pushyamitra who in 184 B.C. overthrew the Mauryas and established the Sunga dynasty was a patron of the Brahmans. Taranatha describes him[175] as a ferocious persecutor, and the Divyavadana supports the story. But the persecution, if it really occurred, was probably local and did not seriously check the spread of Buddhism, which before the time of Kanishka had extended northwards to Bactria and Kashmir. The latter territory became the special home of the Sarvastivadins. It was in the reign of Pushyamitra that the Graeco-Bactrian king Menander or Milinda invaded India (155-3 B.C.) and there were many other invasions and settlements of tribes coming from the north-west and variously described as Sakas, Pahlavas, Parthians and Yavanas, culminating in the conquests of the Kushans. The whole period was disturbed and confused but some general statements can be made with considerable confidence.