Complex sentence: They were warlike and preyed on neighbors to defend their own territory; in 1760 Eastern Atakapa Chief Kinemo sold all the land between Vermilion River and Bayou Teche to Frenchman Gabriel Fuselier de la Claire, the angry Appalousa exterminated the Eastern Atakapa bands.
Split into simpler sentences: They were warlike and preyed on neighbors to defend their own territory. In 1760 Eastern Atakapa Chief Kinemo sold the land between Vermilion River and Bayou Teche to Frenchman Gabriel Fuselier de la Claire; the angry Appalousa exterminated the Eastern Atakapa bands.