 Both in human and monetary terms, the Seminole Wars were the longest and most expensive of the Indian Wars in United States history.The original indigenous peoples of Florida declined significantly in number after the arrival of European explorers in the early 1500s, mainly because the Native Americans had little resistance to diseases newly introduced from Europe.Spanish suppression of native revolts further reduced the population in northern Florida until the early 1600s, at which time the establishment of a series of Spanish missions improved relations and stabilized the population.