Like others I'd rather see them go back farther in time rather than go forward. TW:Bronze Age or TW:Stone age. Only possible exception to that maybe would be Meso-American where they have the North, Central, and South American version. Include the Incas, Aztecs, Mayas, Hopis, and etc. Have the cut off just before the Spainiards arriving to the new world. Something like that would be cool I think. Leave the post-gunpowder weapons out of it.