Since the discovery of L’Anse aux Meadows in Newfoundland in 1960, the picture began to emerge that the Norse (I hesitate to say "viking" because that is a verb, not a noun) beat Christopher Columbus in discovering North America by up to half a millennium. However, L'Anse aux Meadows was not a long-term settlement, and doubt had been cropping up about whether or not the Norse reached further inland (the uber-controversial Kensington Runestone brings to mind.)

We know that the Norse who discovered America were of the Greenlandic or Icelandic branch(es), separate from the mainland Scandinavians. So in this alternate history scenario, those Icelandic or Greenlandic Norsemen made a long-lasting, permanent empire (at least 500 years long) out of any piece of North America east of the River Mississippi, intermarrying the Natives who lived there and even fusing the two (fundamental) cultures together, creating a Native American ethnicity somewhere close to this propaganda portrait by Theodore de Bry:

The question isn't whether or not this is possible, but what point of departure do I need to make this possible?

The main problem with the Scandinavian attempts to colonize continental North America is that they were never serious about it; there were never more than a one or two hundred Scandinavians in North America, excluding Greenland of course. You don't take a continent with a two hundred people.

In 986 CE, a Scandinavian merchant named Bjarni Herjólfsson sailed from Norway towards Iceland to visit his father, who had a farm there. Arriving in Iceland, he found out that his father had left for Greenland with Erik the Red; as a consequence, Bjarni Herjólfsson left from Iceland towards Greenland.

En route from Iceland to Greenland, Bjarni's ship was blown off course by a storm and arrived on the shores of a lush verdant land well west of Greenland. After repairing his ship, he sailed north, and spent some time looking for Greenland, for neither he nor any of his crew had ever been there. Eventually they found Herjolfsnes, a Scandinavian settlement in Greenland, and Bjarni was reunited with his father.

Word spread about the land seen by Bjarni, the Greenlanders being most interested in the reported abundance of timber. Leif Erikson, the son of Erik the Red, armed an expedition to go look for Bjarni's land; this would have been around 988 CE.

Point of departure: The expedition really ought to have been led by Erik the Red himself, not by his son Leif. In real history, Erik suffered a riding accident, so that we was unable to go exploring. Had the expedition included Erik the Red, with his strong personal authority, the attempt to move west would have been treated more seriously.

Leif and his men overwintered in a fertile and green country, full of vines and grapes, which they called Vinland. It is possible that the archaeological discoveries at L'Anse aux Meadows in Newfoundland may be the remains of Leif's camp, Leifsbúðir. When spring came, Leif and his men left and returned to Greenland with a cargo of grapes.

Point of departure: The expedition, instead of one ship and 35 men, has three ships and 100 men, brought from Iceland and Norway in addition to Greenland. Instead of visiting over winter and leaving, two ships and 70 men remain in Vinland and fortify the camp, and one ship is sent back to Greenland, Iceland and Norway to drum up colonists desirous of settling in a new, green, fertile land.

In real history, Leif never returned to America. Instead, his brother Thorwald came for a visit in 1004 AD. He promptly initiated a deadly conflict with the natives, as if he wanted the colonization efforts to fail. He was followed by Thorfinn_Karlsefni who led the only real attempt by Norsemen to colonize the New World.

Point of departure: instead of a pitiful and half-hearted attempt with two hundred people, the Norse come with a thousand people in 20 ships, mostly from Norway and Iceland. Their settlement holds off the natives, and thrives...

If one man had not fallen off his horse, if the Norsemen would have shown a minimum of diplomacy, and if the colonization attempt had been just a little more serious, a Norse empire in the west could have arisen to rival their success in the East, where the Rurikids created what would later be the Russian Empire.

Hat tip to Mark Olson for finding the perfect motivation factor for a sustained attempt at colonization: the Norse settlers in Newfoundland find the Grand Banks; a fishing a fish-processing industry emerges, anchoring the colonists in the newly found land.

Might seem a little obvious but

Don't get attacked by the Natives

It seems there were a couple of key interactions which, if they didn't end in violence, would have meant a prolonged settlement:

• Thorvald: History is muddy so no one is quite sure what happened but this first interaction between Natives and the explorers ended badly with the Norse killing all but one of the group they encountered. The one who escaped returned with an overwhelming force.




• Freydís: The driving force behind this next expedition it seemed she was a little more successful, actually trading with the Natives. Again history is muddy so the exact why is difficult to determine but Natives attacked again and drove them back.

Because accounts of the time are so vague it gives you more or less free reign to say these attacks were misunderstandings and, in your world, simply just don't happen. To go a little deeper perhaps we could suppose Thorvald was just more prone to violence than Leif (his brother who had first landed there) and ifin fact several he hadn't been the one to make first contact then we could say this meeting goes well and the Natives are less suspicious.

Once they had a foothold in the Americas that settlement would thrive. Greenland hadn't turned out to be the lush fields most had imagined so would be happy to move on to somewhere with trees and wild game. These trees would also prove key for trade with Greenland which was sorely lacking in pretty much anything that grows.

This aren't the only interactions between the two peoples but it seems these first impressions were prophetic.

Link to a more storified video on the history

This is more a way to help Alexp's and Lio's ideas than something viable by itself.

The main reason there was no sustained colonization effort is the travel connection Greenland became almost uninhabitable, at least to Norse trying to maintain the typical Norse lifestyle. Greenland did no mesh well with Norse agriculture or livestock, once the little ice age set in this miss-match turned into outright famine. Greenland lacked the strong soil and high turnover forests the Norse were used to so they ended up depleting both, and a Norse civilization that can't farm, cook, or build boats is doomed.

Since the colonies will be cut off they need to be self sustaining pretty quickly which means you need a lot of people fast, But even that is iffy, the little ice age would have hit them as well, they are in for a hard time.

But there is one other thing you can do as an alternative or to help colonies along, have the Greenland colonists adopt a a more sustainable lifestyle. Maybe a disease hit the cattle early one causing a switch to sheep (which are not nearly as hard on the soil). If they start burning coal instead of wood for cooking they would not have depleted their timber supplies as quickly, this is tricky however is you can't cook with coal like you can wood, you really need ovens, coal smoke mixing with food is not pleasant. They could later adopt timber protection laws the way iceland did. If the greenland colonies had survived even in a weakened state there would have been sustained trade and a flow of further colonists with North America, that could bolster a larger colony like AlexP recommends. As technology improved this would lead to more and more travel and trade with the locals, to the point later European colonization would have been nearly impossible.

*Clarification - by point of departure I understand departure from our timeline, not some place ships could leave from.

Mound Builders.

Instead of contact only with the hunter / gatherers of the far north, the Vikings come into contact with the sophisticated culture of the Mound Builders at their outpost in Vinland around the year 1000. The Mound Builders have copper technology, agriculture, long distance trade routes and enough surplus population to build the mounds that are their legacy. Perhaps the Mound Builders are there to trade; they encounter the Vikings and recognize an opportunity. As do the Vikings.

The Mound Builders invite the Vikings to visit their lands further south and strike up a productive interaction - just as they appreciated the opportunities offered by France and Ireland (and Italy) the visiting Norsemen find these lands more pleasant than the far north. Additionally the Mound Builders are more civilized and physically more attractive to the Norse than the Inuit were. The Norse are treated respectfully and well by the civilized Mound Builder people. The native Americans realize they have a lot to learn from the vikings and proceed to learn it from the original vikings they encounter as well as those Norsemen who follow, settle, and begin to interbreed over the ensuing 150 years.

Within 2 generations, the coastal Indians who have learned Norse metalworking and shipbuilding tech (and who have begun to breed horses!) have conquered their neighbors and imposed a "Pax Romana" on the formerly squabbling groups of the interior and southerly coast. Population increases during the following prosperity.