Hernando de Soto was a Spanish explorer and conquistador born in 1496 in Spain. He is best known for leading the first European expedition deep into the territory of the present-day United States, exploring areas that are now part of Florida, Georgia, Alabama, Mississippi, and Arkansas. His journey took place between 1539 and 1542, during which he sought gold and other riches. De Soto's expedition was significant for its encounters with various Native American tribes, including the Mississippian culture. Although he did not find the wealth he sought, his explorations contributed to European knowledge of the southeastern United States and paved the way for future exploration and colonization.