In the sixteenth century, the Lower Mississippi Valley captured the attention of Spain. With colonies scattered throughout the Caribbean and Latin America, the Spanish crown and Spanish adventurers looked to the northern shore of the Gulf of Mexico for new empires to conquer. Early Spanish explorers of the region reported Native American rumors that a fountain of youth and cities of gold might be found in the southeast. They also reported that a great river emptied into the Gulf of Mexico, igniting among Spaniards a lust to locate the river that they hoped would provide a shortcut to Asia. In 1537, King Charles V of Spain named Hernando de Soto governor of Florida. Soto was a conquistador and slave trader, who had achieved extraordinary wealth through his exploits in Central and South America. Upon his appointment, Soto made a reconnaissance of his dominion, hoping to find, as he had further south, an abundance of gold, silver, and other riches. Soto expected that accomplishing his mission would require a long time and necessitate the subjugation of Native Americans. Consequently, he traveled with 650 men (mostly soldiers but also priests and skilled craftsmen), more than 200 horses, hundreds of pigs, and dogs specially trained for warfare. Between 1539 and 1542, Soto carved a circuitous route through the southeastern part of the United States, leaving in his wake a legacy of death, disease, and distrust.