|Information in this article is non-canon|
For long centuries, the Great Valley, then called Sharptooth Valley, had been inhabited by Two-Claws. One day, Flatheads came and invaded the land and there were heavy casualites involved on both sides. Eventually, the Sharpteeth fled.
Longneck members of the war and the conflicts that followed were the Old One and Doc. A member of the Sharpteeth side was the Meanest Sharptooth. Eventually, the Sharpteeth gave up, or so it seemed, living in the Valley of Sharpteeth instead.
The residents of the Valley of Sharpeeth had a prophecy that the first of their kind to hatch in the Great Valley would be the one that would "overthrow the Great Valley leadership and put things the way they were supposed to be".
This war was rekindled, albiet as the Great Valley War, in part by Red Claw, who got the Valley of Sharpteeth to try and seek revenge on the Great Valley.
The ultimate aftermath of this came when Chomper took over the Valley of Sharpteeth as the new pack leader and ordered a ceasing of all hostilites with the Great Valley, at which Chomper and his mate were allowed to live in the Great Valley and the Longnecks and others were spared death.