Hi!
Actually, there are a few aspects in the extended parameters which may have a positive impact on your chances:
1. Number of civs: The default numbers are rather conservative. For a MEDIUM world, go for those 100 civs -> overcrowding gallore.
2. No high savagery: Civs won't settle in high savagery areas (I don't know about secondary settlements, though), so high savagery areas could turn into buffer zones isolating civs from each other.
3. Population cap: You can nullify that value. Actually, you should. This way, you will get those great empires spreading the map...
4. Caves: Caves hamper civ development as the inhabitants attack and sometimes even destroy settlements.
5. Terrain variation: If you set these values very low, maybe even two-digits, you will get connected zones of similar nature, like long mountain chains or great plains. This should help avoid the situation that dwarves live in one mountain chain and goblins in a completely different one. Having great forests also helps keep the elves in play as they need a large hinterland if they are to survive contact with the humans.
6. Terrain types: Kick out all unhabitable terrain: oceans, swamps, deserts. You may also consider reducing good and evil. It seems that evil can only be inhabitated by goblins if we are talking evil mountains and good forests are a place elves can found their retreats. Other races seem to find them a barrier.
7. Historic Figures: Well, this is just a thought and it may be completely wrong, but since culling affects history development, it may be worthwhile turning it off in hope to have more reasons for war. Again, I do not know whether this is the case.
With these measures in place (and of course ignoring megabeast death), you could try generating a world and then look in legends for an era with lots of unfinished wars. Create a world with the same seed but with the ending date right in the middle of it, and at least theoretically, you should have your little war world.
Good luck!
Deathworks