Gath was one of the five cities of the Philistines, a possibly Indo-European tribe which warred with the Hebrews. You might have heard of one of their national heroes, Goliath. (He'll probably be more effective in Dom 3, when you can forge him a black steel helmet and avoid those irritating sling stones to the head - although he's also a good example of the principle that heroes *can* be taken down by lucky shots from some untrained slinger fresh from the sheep pasture, just like happens annoyingly often in Dom3.
)
They apparently had iron-working technology before many surrounding peoples did, although that may or may not be reflected in the Dom3 version.