@NikeBG, in general they are singing about the land and people in it. Ganga’s history is wrapped in some myth and legend. I heard from a young age ganga was used in Herzegovina as a way of communicating from village to village between the mountain valleys. The valleys would carry one’s voice farther so ganga was sort of a ‘news service’ that conveyed information between villages similar to smoke signals attributed to Native Americans. Ganga was also an intimidation tactic as Christian bandits (hajduci) would regularly raid Turkish caravans sort of like a war cry. I can imagine its a bit intimidating hearing all these shouting voices right over the mountains and hills. 

We’re not sure what music Croats were listening to in the middle ages but the ganga culture is ancient and probably has its roots in the Dinaric highlands. A similar phenomenon can be found among Albanians which they call “Kenge” which is just Ganga in Albanian. Its a safe bet that most music was done primarily with vocals with limited instrumentation (perhaps bagpipes or what we call gajde and diple). Another safe bet is to assume there was a lot of church based music too similar to monks chanting since Herzegovina and Dalmatia in particular were home to many many monks.