Asoka (Emperor of Mauryan dynasty) was the Indian ruler who converted to Buddhism as he felt guilt over the bloodshed and horror he caused during the Kalinga (modern Orissa) war. The Kalinga War was fought in 261 B.C which changed Asoka from Chandasoka (Asoka the wicked) to Dharmasoka( Asoka the righteous). After the war he gave up his policy of conquests and now began to work for mankind and spread of Buddhism.