Asoka (reigned ca. 273-232 B.C.), the third emperor of the Maurya dynasty, is considered ancient India's greatest ruler. He combined the piety of a saint with the practical qualities of a king, and in the history of Buddhism he ranks second only to Buddha.

By the 3d century B.C. the kingdom of Magadha under the hegemony of the Mauryas controlled almost the entire Indian subcontinent. Only the southern tip of India and Ceylon remained free of the Mauryas' political influence. However, Buddhist missionaries of Asoka extended religious influence into Ceylon, which became a stronghold of Theravada Buddhism through Asoka's efforts.

In his youth Asoka served as viceroy of Taxila and later of Ujain. He came to the throne in 273 B.C., but a disputed succession delayed his coronation until 269. In 261 he annexed Kalinga, a vast tract between the Mahanadi and Godavari rivers, killing over 100,000 people and...