@Parmandur, that was helpful.
I will probably have the Jotens mountainrange in SE Flannaess be the homeland of the Goliath, because of the proximity of both Fire Giants (Hellfurnaces) and Frost Giants (Crystalmist) along with Stone and Hill. I am guessing Storm Giants are nearby in Jeklea Bay (which seems hurricane areas with islands called "Flotsam and Jetsam". The Goliaths seem to have extended from there across the subcontinent of Flanaess before the arrival of Humans.
Now to think about Dragonborn. There is actually a place in planet Oerth called "Dragon Island", said to be ruled by a "dragon prince", according to the quasi-official world map in Dragon magazine. I wonder if there is a suitable place in Flanaess. The place makes most sense if all Metallic and Chromatic ancestors can be found nearby.