INDIANS. Ethnologists have identified hundreds of groups of Texas “Indians,” as the first European explorers to arrive called the peoples they found. Some of these were true tribes, accumulations of families or clans with social customs, traditions, and rules for order; these were occasionally quite large. At the opposite extreme, some were merely small family groups whose names or ethnic designations were taken for “tribal” names by the Spanish and French and in subsequent secondary literature. The extant names of Texas Indian groups present a dazzling array of variants, partly because the Spanish, French, and English heard the newly “discovered” peoples differently and recorded their names differently. Some names in the historical records are mistakes for groups that never existed.
Full article on the Texas State Historical Association's Handbook of Texas Online