LOL!!
IIRc there is a roadside plaque in Western NC, near Dillsboro/Sylva stating DeSoto passed that way. Don't know how that was determined.
If he wanted gold the Indians told him to go East by SE. If he wanted iron ore (Iron Pyrite) to go SE.
He sent a wagon SE ~ and found iron not far from Laurel, Indiana.
The Spaniards in some way marked the highest point in the Easternmost Cordillera to delineate Protestant lands to the East to the Coast and Spanish lands to the West all the way to the Great Ocean.
This would have been done sometime between 1598 and probably the 1640s.
There was a boundary stone set South of there in what is now South Carolina but the surveyors were killed by the Indians after 2 years. There were other more successful ventures in setting stones further North in Virginia and what is now West Virginia.
Remember, until Spain cramed down the 1604 Treaty of London NOBODY BUT SPAIN had rights in North America (outside of a residual Portuguese right in Nefoundland).
When Philippe I/II (former king of England in the time of Mary) died in 1598, his much better wrapped son Philippe II/III took over things and decided Spain had quite enough to do in the Americas and other elements in the Hapsburg Empire needed to be brought in on the act.
He then turned to a life of partying and travel. He was, after all, the richest man in the world and king of the most powerful nation on Earth.
Frankly, you should read about this guy ~ quite impressive.
30 years ago I had a couple of meetings with the state archeologist in Asheville documenting a relic I had found.
He told me that there were confirmed finds of Spanish exploration era relics in the Murphy area which is only a few days walk from Dillsboro.