Mar Aggai was one of the earlier leaders of the Assyrian Church of the East. According to tradition, he was one of the seventy apostles who, when Jesus divided the world into various mission regions, was given the area of Mesopotamia as far as the border of India. He was appointed by Mar Addai to be his successor shortly before Addai died. Mar Aggai, like Addai before him, sent missionaries to the east. He is said to have been murdered in church by one of the sons of King Abgar V of Edessa. Shortly before his death, Aggai is reported to have appointed Palut as his successor.
Baumer, Christoph (2006). The Church of the East. London: I. B. Tauris & Co. Ltd. ISBN 184511115X.