This story is a perfect example. The Spanish made contact with this city and retreated but they left behind smallpox, and other diseases that wiped the area out making it a piece of cake for later Europeans to move in. Some say pigs were a major disease vector. The Spanish would leave pigs behind in an initial exploration as a future food source. The pigs multipley and expand cleaning out areas that never saw a European.
Ping
The Spainish did a couple of things to help them explore, one was to take pigs onboard ships and when they got close to islands they would throw the pigs overboard. The pigs would then swim to the islands and populate the islands with future sources of meat for the Spanish Fleet when they were plying the Waters of the new world. Another, which is chronicled in the travelogs of DeSoto, was to drive small herds of pigs with them and essentially bring their own lunch. Pigs carry disease which are transferable to humans, and the Indians contracted these diseases and died off as a result. There are accounts of large hanging Gardens down where DeSoto was exploring which no longer existed a mere hundred years later because the populations had died off or deserted them and nature took over.
I have read that nearly all wild hogs in The South are descendants of DeSoto’s herds that escaped into the woods.
They nearly wiped out the Southern Coastal Tribes, Choctaws, Chickasaws, Creeks, et al. Not thru disease but thru destroying their crops..................
IIRC, The pig disease spread to the deer population is one theory on how DeSoto’s trek to the mid continent eventually wiped out those civilizations by killing off their main source of local protein.
Coupled with European diseases it was a double punch.