I'm afraid I am kind of stuck when it comes to creating the worlds history. The current state of things, like powerful factions and control over areas, should be connected by events of the past and not just exist in a vacuum.
But I find it really hard to come up with any real good stories.

Very early on, lizardfolk shamans led a revolt against their naga overlords and turned the capital city into the large temple city it is today.
Some 400 years ago, lots of human mercenaries were hired as caravan guards and auxilaries and they eventually settled down in the region.

But apart from that, I really have no ideas that are in any way interesting.
Maybe add a purge against warlocks here and there, but that can be made a big deal only two or three times.
All the big fantasy histories are all about some super evil almost consuming the world, which I specifically don't want to have.