Which of the following was not one of the Five Civilized Tribes?

The Sioux were not one of the Five Civilized Tribes, which included the Cherokee, Choctaw, Creek, Chickasaw, and Seminole. The term "Five Civilized Tribes" refers specifically to these tribes because they adopted certain cultural practices from European Americans, such as written language, agriculture, and constitutional government, during the 19th century.

The Sioux, on the other hand, are a Native American tribe primarily located in the Northern Plains and are known for their distinct cultural practices, including their nomadic lifestyle focused on buffalo hunting, and a different historical trajectory compared to the Five Civilized Tribes. Understanding the context in which the Five Civilized Tribes are discussed highlights their adaptation efforts in response to European American pressures, whereas the Sioux represent a different cultural and historical experience.