MNblockhead
A Title Much Cooler Than Anything on the Old Site
I'm going to proceed from the assumption that the 1250BC date has been chosen for the state of European and African technology and political organization. So, the assumption is that the Native Americans have c1492 RL tech and the "Old World" (this setting's New World) has the tech it had in RL 1250.
in 1250, Greece is pre-Classical - heck, the Greek alphabet hasn't even been invented/formalized yet. Egypt is at its height or maybe past its prime? In Europe, the Celtic culture isn't even really a thing, yet.
To get the Native Americans to c1492 levels by 1250BC, I think you need a much more competitive American milieu. Maybe a lot more Asians hunt and fish their way into the Americas, at least 15,000 years ago. Maybe their fleeing something in Asia? How NAs get so advanced so quickly is what I'm trying to get at here. Answering that question could help define the setting.
Yeah, maybe not the best approach. But you could start at around 1000 AD.
The Norse from Iceland almost had a permanent settlement at the northern tip of the northernmost tip of Newfoundland (google "L'Anse aux Meadows") around the year 1,000. It failed (based on the legends recorded in the Saga of Greenland and the Saga of Eric the Red) because of infighting among the settlers and constant hostiliteis from the natives whose lands the Icelanders were encroaching upon. If the Norse were able to gained a stronger foothold, not enough to conquer vast areas and peoples but enough to maintain a strong permanent presence with trade and eventual transmission of shipbuilding and metal working knowlege to the Native Americans of the North West.
I'm not sure how strong trade routes were between Iceland and the rest of Europe at this time. I don't think that the Native Americans would get nearly 500 years of breathing space, taking advantage of Norse metalworking and shipbuilding skills. If there was strong, continual trade tie between Iceland and North American, I expect other European nations would have made their way their centuries earlier. The interesting question is whether the Native Americans would have been better situation to quell European explorationan and colonization of the New World if their had been more lasting and meaningful exchanges with the Norse.