The Mississippian Indians were known as the smartest or most complex Native American Group. They were advanced for many reasons. For one, they were mound builders and farmers. Because of this, they used their techniques to trade across the whole of America. Hernando de Soto was a Spanish explorer who came to the Mississippians. He was very cruel to them for he starved them, and killed many of them also. This is how the Mississippians ended.