Around 4000 years before humans arrived in Arland, (-3913 KR to -3909 KR ) there came a war that lasted for four years; each one colder and more bleak than the one before it. It was the war of the Frost Giant king, Renezah.
In the south, the Malanari elves had begun to tap into the arcane flows and realized that where the flow was strongest - a nexus - it was easier for them to draw more energy and cast their mightiest of spells. Arcane nexi of sufficient strength to feed their growing addition were rare and difficult to find so they tried to 'damn' the flow to create their own magical pools from which they could draw. Since the Dwarves in Grandfather mountain had no knowledge of the Arcane and the Gnomes were too far away to feel the effect - or so they thought - the draining of energy from the arcane flow would not be noticed. The particular stream that they were tapping into was also the very same stream that traveled into the Northern Reaches and in a weird twist of fate, it was the same stream that fed Renezah's kingdom.
Though it is unknown as to why or how, the farther north one travels, the arcane streams grow fewer and weaker until, eventually, they vanish entirely. It is for this reason that the elimination of one of the last fonts of arcane energy drew such ire from the Frost giant king.
By combining the wintry abilities of his people into a unified front, he was able to create a miniature ice-age that brought snows with his army and covered the land in winter for one hundred years. His army drove the early Mountain-Dwarves into their stronghold of Grandfather Mountain and had pushed deeply into the great forests of the Sylvanari.
By this time, the Tauric nations had set-sail and left for the lands to the West centuries earlier and so the nations of Elf, Dwarf and Gnome had to unify to drive him back. The Gnomes, with their powerful 'Warforged' creations launched the first counter attack, driving a wedge down into the invading forces from their home in the Shield Mountains.
Insert Big Battle here
At the conclusion of the invasion, the Turzul were banished from Grandfather Mountain for their philosophy of overt destruction not only against the Frost Giants but also the Elven, and Gnome allies. Because of the strict policy of not assisting their allies in the war, the Shield Dwarves decided to leave Grandfather Mountain and the authority of the High Thane Under the Mountain.
The Crysanari were a young nation within the Elves at this time, their use of Griffons as mounts was just starting but it gave them a decided edge in any engagements with the Frost Giants. Excellent in guerrilla warfare against the casters of the Frost Giant army, they grew to hate the use of Arcane energy in all beings. At the end of the war they decided to leave their forest home to the vast Ivory Plains to the west rather than remain with the Sylvanari who were embracing its use amongst their cousins, the Malanari. It was the firm belief of the Crysanari leader that the Malanari's study of arcane magic that brought the Frost Giant army upon them. The Malanari, not wishing to involve their cousins with their new talents also decided to leave and settle in what would become the South Marches along the southern ridge of the Grandfather Mountain.
The Gnomes suffered their greatest schism during the height of the war with Renezah and his forces. Those gnomes that eventually became known as Berkeron began animating the corpses of the dead frost giants as well as elves and dwarves to turn them against the invading army. This lead the Gnomes who followed the Arcane paths of Gizad to leave their ancestral home en mass to relocate to the island at the center of the Sentinel Sea; Tor Gizad. As they left, the Gizadi took with them the sum total of the Gnomish library of arcane sciences to prevent their cousins, the Berkeron from perverting the use of magic. The hatred of the Berkeron knew no bounds and so the Ulevar were left to take the brunt of their hatred; eventually driving them out as well.
This lead to what became known as the Golem Wars.