The Burnt Gate, originally called the Blackmoor Gate, was the earliest recorded connection between the worlds of Eamon and Mystara (though earlier undocumented ones are certain). Fragmentary records from the Old Empires suggest that the rift formed around 2900 BA in a valley in northern Ervuol near the border with Lanst, not far from what is now the city of Knarwich in the province of Gwill. Its terminus on Mystara was located near a wooded road a few miles outside the city of Blackmoor on the continent of Skothar.
Blackmoor and Ervuol both discovered and secured their local ends of the rift, then sent explorers and later emissaries through to the other side. The relationship between Blackmoor and Ervuol, while cautious, seems to have been a positive one that prompted at least some trade and sharing of knowledge.
This relationship ended abruptly in 2777 BA when some great engine or weapon on Mystara detonated, releasing a blast of such intensity that it annihilated Blackmoor and knocked the world off its axis, with the resulting Great Rain of Fire spreading devastation across the planet. On Eamon, a jet of flame, ash, and white-hot debris shot through the rift, incinerating everything in the surrounding valley. Great waves of arcane magical energy also passed through, causing widespread magical disruptions which were eagerly studied by the Talus Assembly.
In the days and weeks after the disaster the fires in the valley slowly burned out. The rift lingered for a couple of years, but had been destabilized and flickered erratically, showing glimpses of the vast, smoldering crater that was once Blackmoor before entirely closing. The charred and irradiated region around the site was abandoned, but life gradually returned over the following centuries. The terminus site on Mystara is now a broken and largely uninhabited wasteland.
Per some undulous planar rhythm, the Burnt Gate periodically reopens in the valley, flickering back into existence for a handful of years every two to three centuries.
