San Antonio Missions National Historical Park contains four Spanish colonial mission sites spread along a 10-mile stretch of the San Antonio River, and is part of the only UNESCO World Heritage Site in Texas. After 10,000 years, the people of South Texas were suddenly faced with the pressures of drought, European diseases, and colonization. In the early 1700s, many Native peoples of South Texas gave up their traditional ways of life to become Spanish citizens, accepting a new religion and agrarian lifestyle in the hopes of survival.