Through the Multiverse
One thousand years ago all gates to Sigil abruptly closed leaving the four worlds closed off from each other. For the past thousand years all those stranded from the great closing have been trying to coexist with the natives of the planet they find themselves trapped upon. Their success has been minimal.
At the eve of the 21st century the first portals opened up in the modern world. These portals at first only allowed travel to different places on the same world. It wasn’t until a few years later that the first travelers from an alternate world made their disastrous entrance into the modern world. What was first thought to be a terrorist attack was later found out to be a series of accidents from two of the other worlds. Airplanes from the comic world and the techno world flew into major buildings on the modern world’s westernmost continent.
In the years following the event have come to been known as the Awakening of Sigil.
The history of the multiverse has seen it’s fair share of virulence’s, plagues, poxes and other maladies that have spread across all four worlds.