From what I have found on ftb wiki ;
the Barako, the Sun Chief is a hostile monster added by Mowzie's Mobs. One spawns inside each generated Barakoa Village, sitting on top of the throne. The Barakoa Village is a structure added by Mowzie's Mobs. It spawns in Savannas.
It would be possible to find more biomes that spawn this mob/village if we didn't have the world border since we do there will be a finite amount.
I have never seen that village spawn in any other dimension.