The most of the information on early Cholas are available in Sangam literature. The other informations are available in Mahavamsa, Buddhist text of Ceylon, Pillars of
Asoka and Periplus of the Erythraean Sea. The most famous king of early Cholas is Karikala Chola. He ruled around 270 BC. He had won the famous battle of Venni in which he decisively defeated Pandyas and Cheras. He is also believed to have won the whole of Ceylon.
But the most important work which he did as a king was to build world’ earliest water-regulator structure in stone at Kallanai on River Cauvery. It was built for agricultural purposes.