High Quality Content by WIKIPEDIA articles! Hernando de Soto (c.1496/1497 - 1542) was a Spanish explorer and conquistador who, while leading the first European expedition deep into the territory of the modern-day United States, was the first European to discover the Mississippi River. A vast undertaking, de Soto's expedition ranged throughout the southeastern United States searching for gold and a passage to China. De Soto died in 1542 on the banks of the Mississippi River at present-day Lake Village, Arkansas.