With the growth of foreign trade, Buddhism also travelled to the Central Asian countries during the Kushana period. Popularity of Buddhism with the foreigners brought its transformation.

For, the foreigners were interested in something about Buddhism which they could easily understand. The foreigners were not interested in philosophical doctrine of Buddhism.

Out of this desire there developed a new form of Buddhism called Mahayana (or the Greater Vehicle) in which worship of icon of Buddha was allowed.

Those who did not share the new idea were known as conservative Buddhists or Hinayana (or the Lesser Vehicle).