Both rivers are said to harbor an extraordinary amount of Paleo-Indian spearpoints, many of which are the large Clovis types that were used for spearing mastodons.
Skipping ahead a "few" years, the Spanish explorer Panfilo de Narvaez arrived in the area in 1528. Hernando DeSoto arrived in 1539. The first fort there was built in 1679, commissioned by the Spanish Florida governor and named San Marcos de Apalache. According to what I read, it stood only three years before it was captured by pirates. http://www.exploresouthernhistory.com/sanmarcos1.html
The land became English in 1673 when all of Florida was transferred from Spain. The British retained the fort during the American Revolutionary War. The land returned to Spain in the 1780s. It was once again taken by pirates as well as Indians, when in 1795, along with the Seminoles, William Augustus Bowles formed a short-lived state in northern Florida known as the "State of Muskogee", with himself as its "Director General", and in 1800, declared war on Spain. Bowles operated two schooners and boasted of a force of 400 frontiersmen, former slaves, and warriors. The Spanish took the fort back a few weeks later.
In 1818, Andrew Jackson took the fort back and claimed it for the U.S. Army, where it was the site for several executions of prominents of the time and Indians. It was changed into a marine hospital for a time before being used as a Confederate fort during the American Civil War. Known as Fort Ward, it was never taken by the Union troops. Soldiers from the fort participated in the critical Battle of Natural Bridge that kept the state capital from falling into northern hands. In fact, it was the only Southern state capital not taken.
This place has very old--- and very bloody--- dirt.