A story in Hindu tradition states that elephants were tamed and made vehicle by humans as a result of a curse by Rishi Deerkhatapas. Legend has it that earlier elephants were blessed with supernatural powers and could fly and take any form. These powers made some of them arrogant.
Once a group of elephants assembled on a banyan tree in the Himalayas . This was a very huge Banyan tree which was spread over 1000 miles. Its branches were so large that elephants used to dance on it.
During the assembly, few elephants climbed on to a branch and started to play on it. Rishi Deerkhatapas was performing Tapas under the particular branch. The dance movements of the elephants became vigorous and the branch broke and fell on to the ground. The Tapas of Rishi Deerkhatapas was disturbed and in a fit of anger he cursed the elephants to lose all their powers and to become vehicles of human beings.
This is how elephants became the vehicle of human beings.