Joana wrote:
The possessive is correct, although the phrasing is a bit esoteric: the history of violence belonging to dwarves and orcs goes back to the beginning of their races.
"There's" would create a run-on sentence with a comma splice; "there's been" would do the same and additionally be a colloquial contraction for "there has," usable in common speech but not in a published text.
Joana, wouldn't there be a need for a comman somewhere in there for "theirs, a history of violence, blah blah" or something like that?
I know it's a minor thing but it struck me as strange and that's why I brought it up.