If we look at world history—I am speaking a little vaguely, since it is not possible to be completely accurate. The human race began from a single region, as you can see in the bottom image.
What kind of effect did these migrations have on language?
The first humans that were in Africa had to use some kind of language for communication, and when these people migrated from Africa to European regions, the migrants created new languages. Now, what I am wondering, since they were not expert linguistics, the languages that developed in these regions must have some kind of influence from their predecessor.
If we look at the languages that exist today, they differ greatly from other regions—here I am talking about the root languages (I am not sure "root language" is the right word here, if someone knows the right word then please edit it.), like Latin, Sanskrit, etc.
So how did these changes occur? The reason why I am interested in this is, I am creating cultures from languages, you can say the influence of language on culture. The first language, Vietrian, splits in two to create Old Viereian and New Vietrian. The basic difference is: "old" is used for spells making, and "new" is used for communication, this also vague since it is a five-page long difference. New Vietrian was enchanted so that the listener listens to it in their mother-tounges. This new language was passed down as "Zirian". From Zirian, every language emerges, except for Necromancers and Elves.