Causes behind spread of Buddhism:

-Buddhism did not recognise the existence of God and Soul (atman).The teachings of Buddha were practical and simple therefore it appealed to the common people.

-Buddhism attacked the evils the Verna System. People were taken into Buddhist order without any consideration of cast. women were also admitted to the Sangha. Therefore, it had a popular appeal.

-Buddhism made a special appeal to the people of non vedic areas, such as Magadha. People of Magadha were looked down by the orthodox Brahamins. Hence they responded readily to Buddhism.

-The use of Pali language of the local people also helped in the spread of Buddhism.

-Buddhism was patronised by several rulers, such as King of Magadha, Kosala, Kausambi, etc.

-During Kanishka's rule that Buddhism reached at its peak, during this period 4th Buddhist council was held and for the first time Buddhism split into two parts- Hinayana and Mahayana.

-Kanishka built a Stupa and Monastery at Peshawar which became a great center of Buddhist learning and Culture.