Answer:
These islands contained large amounts of gold, spices, and copper.
Step-by-step explanation:
Back then, it was said that Georgia was really rich in several good that was for Crown interest. The principal interest was the gold, because Spain Crown was supported and maintained by the Gold, they were really wasteful.
That's why was attractive for them.
Personally, Hernando de Soto wanted to achieved a higher social rank as a marquis, so that's why he was the first in enter those lands.