The broad label "indigenous groups" or "Native Americans" applies to literally hundreds of diverse groupings of people in the Texas territory. Not all of them could be described precisely as tribes, either, as many of these groups were large clusters of families, clans or other associated groups with distinct customs, organization and behavior. According to the Handbook of Texas Online:
"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." 
In short, the indigenous peoples of Texas comprised a large, diverse and evolving set of groups, as many of these groups migrated or were forced out of the territory by new groups, or were absorbed or recombined with groups of similar cultures, or extinguished as identifiable groups through conquest.
The great number of indigenous groups resulted in a great variety of social organization, values, and practices - a great variety in political culture, if you will. Some groups, most famously the Apaches and Comanches, who came to the territory after the Spanish arrived to be nearer to supplies of horses, were very aggressive and warlike, living on the spoils of raids and conquest. Other groups like the Caddos were primarily engaged in agriculture, while still others like the Wichita engaged in a mix of hunting, trade, and some warfare.
The expansion of Anglo American settlements in the eastern part of the continent, led to new waves of Native Americans, notably the Alabama, Coushatta, and Cherokee tribes, among others. Some of these tribes naturally migrated to Texas in search of fresh hunting grounds as their traditional hunting grounds in the east were depleted by Anglo settlement. Others were more forcibly pushed out of their native lands by the Anglo settlers or the U.S. government for various economic or overtly political reasons. Some groups from the Delaware Indians fled their lands in the east, for example, after siding with the British in the War of 1812.
The diversity of experiences and cultures of Native Americans in Texas suggests caution in making generalizations about their contribution to the overall political culture of Texas. Still, it is reasonably safe to say that like Spanish and Anglo American settlers, the Native Americans found life "on the frontier" to be harsh, intensely competitive, sometimes violent, and often solitary, with uneven and constantly shifting public authorities (whether indigenous or European) for governing daily life. One cultural trait broadly shared by the Native Americans was their rejection of town life - observed by the resistance of the relatively peaceful natives in East Texas to settlement in the Spanish missions - in favor of an independent lifestyle in the open countryside.
The culture of the indigenous groups has been largely extinguished or marginalized in contemporary Texas, with three reservations representing the only organized settlements of Native Americans in the state, according to the Handbook of Texas. Nevertheless, the 2000 census reported that over 118,000 people in Texas (or 0.6 percent of the population) identified themselves as American Indian. Beyond the numbers of Native Americans in the state, the cultural traits that were shared by many of the indigenous groups - competition, individualism (especially notable in groups like the Comanches) - persist today.
1 Handbook of Texas Online, link: "INDIANS," (accessed Jan 25, 2006).
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