The Northlands were created with the rest of Steorth, and were originally just a land of gentle snowfall and tall peaks with a great view for a million miles in all directions a clear day. When Tai'kalu constructed a fortress high in the mountains, Tylbur cursed all of Steorth, and the Northlands were afflicted with a massive and terrible blizzard that has not stopped nor lost strength since. Not much is known about the Northlands nor any civilisations in the region prior to the curse of the blizzard.
Near the end of the Second Age, as Tylbur wrote the Prophecy of the Second Rebirth, Tai'kalu grew angry with Tylbur for a reason yet unknown. Tai'kalu sent out his forces to ravage all of Steorth, particularly targeting the central land of the Kingdom of the Phoenix - Tylbur's people. The forces of the Kingdom fought with great strength, but not without incredible loss. The Order of Scholars were especially targeted, and their great library in the Duchy of Erye was burnt to the ground; this caused many long-term ramifications for the whole of Steorth, thus aiding the conquest of Tai'kalu in the long run. This conflict became known as the First War of the Northlands, and it ushered in the Third Age.
In the Fourth Age, a smaller skirmish occurred, as Tai'kalu attempted to take over a second time; though with his weaking in the First War, he was brutally defeated. This conflict, though very small compared to the First War, became known as the Second War of the Northlands. Since this conflict, Tai'kalu has been gathering strength once again, to attack one final time in a final attempt to take over.
Because of the harsh nature of the land, not many venture this far north. The blizzard does not affect all of the Northlands, however, as the lower regions of the region are much more gentle and habitable. The city of Natrhok is the only city in the region that isn't constantly battered by the blizzard, because it is near the holy site of the Lake of Tylbur's Tear, which is a lake of warm water: a source of warmth and life in an inhospitable frozen wasteland.
The Duchy of Pinewood in the Kingdom of the Phoenix is technically part of the Northlands, but is much more habitable and beautiful than the rest of the Northlands. The Duchy was acquired by the Kingdom of the Phoenix after the First War of the Northlands and has been under Kingdom control since.