Guna were indigenous people inhabiting Northern Colombia and the Darien Province of Panama at the time of the Spanish invasion. Only later they began to move to the islands, towards what is now Guna Yala. There were two reasons for that: a conflict with the Spanish and other indigenous groups and mosquitos.
Why should you visit San Blas, Panama
San Blas consists of 365 islands, some of them small enough to hold only two palm trees and a hammock. It is an absolute paradise featuring private islands, sandy beaches, coconuts, and the most beautiful seashells I have ever seen.