The Degan name, although having roots in various locales, is thought to be of Germanic origin, with many of the surnames having an additional "Von", i.e. Von Degan, etc. In other languages the name means "coconut meat."
There are several similar surnames in German that are related phonetically, being derivatives. There are small enclaves in Bavaria which carry the Degan name. (My own name, Roy Elwood Degan III actually means "King of the Wooods" of DEGAN, a small feudal lordship of southern bavaria.
As a result of the european military campaigns, crusades, wars, plagues, and general commerce, the descendants of these hessians migrated to other domains to establish themselves, mostly westward. However, I have found several Asian families who carry the surname.