From there he sailed down the east coast of India and visited south India and Maharashtra. He returned north and stopped at Nalanda again and then spent some time nearby studying non-religious subjects, such as mathematics and geography, with a famous teacher. Xuanzang was sent to Gauhati, the capital of Assam, to convert the King to Buddhism. Back in Nalanda he took leave of the monks and headed back to his native country in 643. 