What was hernando de soto main motivation for exploring the southern united states

The expedition of Hernando de Soto to the current states of Florida, Southeast (Georgia, the Carolinas, Tennessee and Alabama) and Middle South (Arkansas, Oklahoma, and Texas), which pursued the same objectives as Juan Ponce de León, Lucas Vázquez de Ayllón and Pánfilo de Narváez, was an effort of conquest that with more than 600 men wandered throughout the Southeast and westward of the United States in search of gold, silver and a passage to China.