The Invincible Golden Horde

The last political organization in Engiziland before the Dragonkill War was called the EWF, Dragon Empire, Youfland, and/or the Wyrms Minds Collective. This was the last sorry refuge of an empire which had once ruled most of Peloria. There the debris of the outlawed dragon mages had gathered to resist their foes. But even though the rest of the world had turned against them, they had not abandoned their unnatural practices.

In 1042 the dragonewts, heretofore neutral through ancient treaties and oaths, rose in revolt from their cities in the heart of the Wyrms Minds Collective to aid the invading humans. This resulted in the final sack of the decayed empire, and for a while no humans ruled in Dragon Pass, though they lived there.

Though no humans ruled in Dragon Pass, many of those outside coveted its strategic position and attempted to rule or possess it. When the dragonewts attempted to intervene for the sake of their nesting place the humans worked themselves into an anti-dragonewt crusade.

In 1120 the invaders mustered together and marched on Dragonseye, the capital of the inhuman Dragonmen, intent upon destroying the primal dragonewt egg-wombs with their newly invented spells. One army, reliably numbered at 70,000 strong, marched south from Peloria. From Prax in the east came a horde led by Jaldon which was boasted as being 100,000 strong, although half that number would not be inaccurate. 40,000 men invaded from the south. Together, they were called the Invincible Golden Horde.

Some humans resisted their fellows. The troll king of the Shadowlands sent 20,000 trolls and 45,000 humans to aid the dragonewts. The native dragonewts also received help from their allies in Ormswood. But these were not important compared to the many dragons, wyrms, and related forms which came from all across the cosmos to answer the call to defend their nest hearts. Their destruction was complete: less than one in twenty of the invading humans escaped alive.

The event is called the Dragonkill War because of what the dragons did, not what happened to them. Most people alive today feel it was a long-term trick which the dragons played on humans in order to get enough of them together in one place to be a great draconic meal.
The shock of these losses was so great that all the people around Dragon Pass feared the region for generations afterwards, and most of them who were close moved far away. 

The dragonewts wanted to keep them away, and they erected a deadly invisible wall around their homeland, called the Deathline. A series of crosses, each topped with a different beast's sculpted head, reached east to west. Even without these barriers the superstitious awe and fear which humans held for the pass were enough to keep even the boldest adventurer out.