Sm Mi O is the first man of Akha tradition, the apical human ancestor at the head of the patrilineal genealogy. During the most important ceremonies the line of forefathers is recited in full, climbing more than sixty generations back to him, and mastery of this chain is expected of every adult man. The genealogy is not merely commemorative: it regulates marriage, for a man and woman who discover a common male ancestor within the preceding six generations may not wed. Legend makes Sm Mi O the offspring of Bhe Sm, so that even the 'first man' is set within the descending order of ancestors that stretches upward to the creator.