Hi CB,
How far back? Well, as far back as there is written information and even further if possible. It's easier for me if I can start from the hypothecized irreducible and work forward. That's true for me on pretty much everything that I put a lot of thought into.
I've read about the hunters/gatherers, the Egyptian and Babylonian empires, the fertile crescent, trade routes, tribal living, their religions, city states and parts of how they functioned, city states making alliances and joining forces for strength, betrayal between the allies, etc. Yes, I think I'd enjoy forays off the beaten path.
Historical novels no doubt are fun to read, but I think I'd do better with a good textbook. Sealynx gave some good suggestions.
Sounds like I'm not the only history lover on the board!
tt