The Caddo is a confederacy of Native American tribes from east Texas, Louisiana, southern Arkansas, and Oklahoma. In 1541, the tribe ambushed Spain's Arkansas River expedition under Hernando de Soto near Caddo Gap, Arkansas, and the tribe was eradicated by smallpox. After the 1803 Louisiana Purchase, the United States attempted to ally with the Caddo tribe, and the tribe remained neutral during the War of 1812. The tribe was moved to the Indian Territory under the Indian Removal Act, and most of its 6,000 tribe members currently live in Oklahoma.