For many years, this area was visited by chiefs and tribes of numerous indigenous peoples. They called it the "Valley of the Vapors" at the time of Spanish explorer Hernando de Soto's arrival in the area in 1541. He was the first known European to see the springs. Members of many Native American tribes had been gathering in the valley for over 8,000 years to enjoy the healing properties of the thermal springs. Around the 18th century the Caddo settled in the area, followed by the Choctaw, Cherokee, and other tribes from the Southeast across the Mississippi River. There was agreement among the tribes that they would put aside their weapons and partake of the healing waters in peace while in the valley. The Quapaw lived in the Arkansas River delta area and visited the springs.