Chajurru (Zyanya Supplement)
From D&D Wiki
 Life and Society:
The major summer ceremonial is the Medicine Dance, which included a secret ceremony for members of the Medicine Dance Society (a religious society open to both men and women) as well as public rituals. The winter feast is a clan ceremonial intended to increase war and hunting powers; the spring Buffalo Dance is a magical ceremonial for calling the bison herds.
The Chajurru are divided into clans that traced membership through the male line. The clans are organized into two phratries, or groups of unequal size: the Upper (Air) division contained four clans, the Lower (Earth) division eight. A marriage partner was always drawn from the opposite phratry, never from one's own.