Vedic culture relations with Islam and Christianity are in some ways quite different from the ties and tensions that bind together religions of Indian origin. Hindus live with a legacy of domination by Muslim and Christian rulers that stretches back many centuries—in northern India, to the Delhi sultanate established at the beginning of the 13th century. The patterns of relationship between Hindus and Muslims have been different between north and south India. While there is a history of conquest and domination in the north, Hindu-Muslim relations in Kerala and Tamil Nadu have been peaceful. Islam came to south India very early, possibly about the 7th century, through traders and sea routes. There is a vast body of literature on Islam in Tamil composed over almost a thousand years. The early 19th-century Sira Puranam, a biography of the Prophet Muhammad, is an excellent example. There are also hundreds of shared ritual spaces, called  gargahs (literally, “doorway” or “threshold”), for Hindus and Muslims. These mark shrines for revered Muslim (frequently Sufi) leaders and are visited by both Muslims and Hindus. Moreover, close proximity and daily interaction throughout the centuries has led to efforts to accommodate the existence of the two religions. One manifestation of such coexistence occurred among some devotional groups who believed that one God, or the “universal principle,” was the same regardless of whether it was called Allāh or brahman. Various syntheses between the two religions that emphasize nonsectarianism have arisen in northern India.