"Sparta, too, institutionalized relations between mature men and adolescent boys, as well as between adult women and girls, and gave them a pedagogical focus. The few accounts we have, all written by foreigners, do not claim that the relationships were a part of initiation rites, but the Spartans were secretive about their institutions, and strangers would not necessarily have learned the details. However, many aspects of Spartan homosexuality and marriage customs point to tribal origins. Participation was mandatory for all youths of good character. There were ordeals - a common feature of tribal initiation. At their conclusion, all boys in the same-age grade had to marry - as in many tribes. Even after marriage, men lived in men's houses, not with their wives. Wives and male lovers were shared with age-mates. Like Crete, from whom the Greeks believed Spartan institutions were borrowed, Sparta preserved ancient customs that had disappeared in other city-states."