Intentional European ventures into the Southeast began in 1513 with Juan Ponce de León. From this time forward, Spain claimed exclusive sovereignty over an area ranging from the Florida Keys to Newfoundland and west to Mexico known as La Florida. Other European powers never recognized Spain's claims over the Americas, and only acknowledged Spanish hegemony in areas of the New World that it had actually settled.

Lucas Vásquez de Ayllón established the first Spanish settlement in the present-day United States in 1526. The ill-fated San Miguel de Gualdape was founded on the Georgia coast among the Guale Indians. Most of the original 600 inhabitants perished, including Ayllón himself, and only 150 eventually made it back to Española. Subsequent entradas into Florida led by Pánfilo de Narváez (1528) and Hernando de Soto (1539) were equally unsuccessful in establishing a permanent presence, accruing wealth, or converting natives to Christianity. Their explorations did have the unintended and devastating consequence of introducing pathogens among native populations who had no immunities to them. In 1565, Pedro Menéndez de Avilés founded St. Augustine, the first permanent Spanish settlement (and the oldest continuously-occupied community in the present-day United States) in territory inhabited by Timucuan Indians.

Spain had a state religion and religious conversion was always a central aspect of their colonization strategy. Missions became the Spaniards’ most effective institution for influencing the native populations, establishing a foothold in hinterland territories, and supporting its capital in St. Augustine. While St. Augustine was geographically strategic in protecting Spanish treasure fleets sailing through the Straits of Florida en route back to Spain, densely populated and extremely fertile Apalachee Province was pivotal to the Spaniards’ control of the Southeast in order to provide labor and provisions for St. Augustine.