A Jewish community in Kerala was probably what drew the Apostole Thomas to Kerala.
South India had trade connections with the Mediterranean and West Asian world since ancient times. This enabled the Church in those areas, particularly Persia, to have a knowledge of the existence of a Christian community in India. Many Christians, when they were persecuted in Persian Empire, fled to the Southwestern coast of India and found there a ready and warm welcome.
There is no documentary evidence referring to the way the Indian Church was governed during early centuries. According to tradition, the successor of St. Thomas corresponded with the leaders of the Christian Churches in the Middle East; and the church of India from time to time was ruled by prelates from that part of the world.
Traditional site of Thomas's landing at Cranganore in Southern India in 52 AD. Here he preached the Messiah to a Jewish colony. They were converted and their synagogue became a Christian church.