Within the progenitors of the Bene Gesserit on Terra, the Mother title was hereditary, and used openly only in the few remaining matriarchal power structures. The Mothers was a representative intertribal group composed by the Great Mother (the lead gene-carrier) of each tribe.
Within patriarchies, the Mothers became a secret order, married to aristocratic leaders and usually having as their Great Mother the wife or mother of the tribal leader. Only some of the Mothers, of all the gene-carriers, retained group consciousness, tribal memories, and perhaps limited prescience.
To the Motherhood these "sybils" formed a network which tied together all the major political powers north and south of the Great Sea.
Within their own order, the Mothers developed their own desire for the power gained from a savior who could understand the future. In some southern tribes, the savior was called Hdarak ("to last, or to be everlasting"), connected to the Bene Gesserit term Kwisatz Haderach