For whom did De Soto claim all the land drained by the Mississippi?

Hernando de Soto, the Spanish explorer, claimed all the land drained by the Mississippi River for the Spanish Crown. Specifically, he claimed this vast territory for the King of Spain, who at the time of de Soto's exploration was Charles V (Charles I of Spain). This claim was made during de Soto's expedition in the mid-16th century as part of the Spanish effort to explore and colonize the Americas.

Hernando de Soto's expedition through the southeastern part of North America between 1539 and 1542 marked the first European exploration of this region. The claiming of lands for the Spanish Crown was a common practice during this era of exploration; sovereigns sponsored voyages with the expectation that the explorers would claim new territories in their name. The concept of claiming land simply by "discovery" and the planting of a flag or a cross was rooted in European legal and religious traditions but did not account for the many Native American societies that already inhabited these areas.

The Mississippi River, the second-longest river in North America, became a particularly important geographic landmark during the age of exploration. European powers, like Spain, saw the control of such rivers as strategic for trade, military movements, and claiming territorial rights. The lands drained by the Mississippi encompass an enormous area, and if these claims had been enforced and maintained, they would have given Spain control over a large portion of what is today the United States. However, Spain's claims were challenged and later supplanted by other European powers, particularly France and England, and eventually, the United States after its independence. The issue of territorial claims and sovereignty over North America was a complex and contentious part of history that continued to evolve through wars, treaties, and diplomatic negotiations for centuries.