February 2017 - Several thousand years after the first people crossed the Bering Land Bridge into North America, other people came to North America by boats, crossing from Siberia across the Arctic Ocean to Alaska. This was about 7000-5000 BC. Archaeologists call these people the pre-Dorset Culture. These people seem to have begun to leave Alaska about 4500 BC, when a warming period melted some of the Arctic ice, and they reached Greenland about 2500 BC. It seems like a long way from Alaska to Greenland on the map, but maps show Canada all stretched out: really it's not that far. (To get a better idea of distances, check out this website). The pre-Dorset people hunted musk ox and reindeer in the north, and further south they hunted seal and caribou, and like most people in the world at this time, they fished a lot.
A second wave of people migrated into the Arctic from the west about 1000 BC. Archaeologists call these people the Dorset Culture, and the Inuit called them the Tuniit. These people were tall and strong, and they seem to have reached Greenland, on the Atlantic coast, about 500 BC. About 200 AD, the Tuniit seem to have abandoned Greenland again, and then around 1000 AD they began to migrate back south into Greenland, at first living mainly in the north and gradually moving south. The Arctic was getting warmer around 1000 AD, and maybe this made it harder for the Tuniit to find and hunt the animals they depended on for food.
The warmer weather melted the ice and made it easier for outsiders to invade Tuniit land. So about 1000 AD, the Tuniit people began to be conquered by a third wave of Inuit people who were moving east from Alaska along the Arctic Circle. The Inuit seem to have reached the Atlantic coast by around 1400 AD. These Inuit people were shorter than the Tuniit, but they had big military advantages because they had dogs and boats and iron tools, and apparently the Tuniit didn't. The Inuit hunted whales and used the meat to eat and the bones to build their houses. They pretty much conquered all the Tuniit.