TANISTRY (from Gaelic tana, lordship), a custom among various Celtic tribes, by which the king or chief of the clan was chosen from among the heads of the septs and elected by them in full assembly.
The descendants of Eogan were the O'Neills and their numerous kindred septs; the posterity of Conall Gulban were the O'Donnells and their kindred septs.
The settlers in the Scandinavian towns early came to be looked upon by the native Irish as so many septs of a tribe added to the system of petty states forming the Irish political system.
They soon mixed in the domestic quarrels of neighbouring tribes, at first selling their protection, but afterwards as vassals, sometimes as allies, like the septs and tribes of the Goidel among themselves.
They even made a great expedition to Ireland, where Bruces brother Edward was proclaimed king by the rebellious Celtic septs, and rode across the whole island, exterminating the Anglo-Irish population in many districts (1315-1317).