Maternal were the basic family unit for the Tonkawas.

After consolidation, the Tonkawas chose a tribal head chief. Maternal clans were the basic unit in Tonkawa society. Children became members of their mothers' clans, and men lived with their spouses' clans. Because each clan saw itself as a family unit, marriage within the clan was discouraged.

Explanation:

disease was the number one killer of native peoples. they had had little exposure to the diseases of europe. this led to some villages being almost completely wiped out and some tribes destroyed.