The traditional region of the Cholas was the fertile valley of the Kaveri river in present day Tamil Nadu. The Cholas ruled this region from the 3rd century BCE. However, at the height of their power from the later half of the 9th century till the beginning of the 13th century, the Cholas ruled a significantly larger territory. They conquered all of South India and Sri Lanka and extended their influence along the entire east coast of India and also to various parts of South east Asia.