Even with WWI and WWII, only very small patches of the thin surface of the planet Earth were affected, and entire races carried on oblivious and ignorant to many of these major events.  Keep in mind that even when there is a major, pivotal event, many groups and realms will still not know about it, or might see it in a wholly different light.

Also, despite many of the timeline events listed below being relatively negative at first glance, it is important to note that far more 'good' was occurring during these time periods, and that all of the species and societies in question were merely trying to find the food they needed and raise their offspring in the only ways they knew how.

This timeline shows how nearly 100% of every story ever told can be harmoniously fused together into our 'omni-verse' here, with narry but a few minor plot conflicts, which we have already begun to cleverly iron-out, affecting their respective sagas, plots, and characters only in the very slightest and most negligible ways.