If there had been any civilised being stupid enough to attempt a cartographic survey of the Realm of Ghur then even by scouring there maps you would not be able to find Embermore.
Such a small insignificant island would almost certainly have been left off any realm map. It has lain largely undiscovered throughout the Age of Myth and the Age of Chaos. Embermores only inhabitants are a tribe of Brayherd. For as long as they can remember they have worshipped the only remarkable thing on the island.
In the centre of Embermore stands a huge shard that sticks out of the ground as if Sigmar himself had hurled it from the heavens. The shard is an almost obsidian black glass substance that is in tune with the winds of magic. For millennia the Brayherd shamans have used it as a giant Herdstone controlling the islands weather and bringing forth plentiful hunting.
Then with the rise of Nagash came a giant storm that lead to a bolt of lightning striking the shard. The resulting shock wave destroyed 90% of the islands inhabitants. When the smoke cleared the shard had been split asunder and spread throughout the island.
Perhaps worse is that every week the entire island now transforms. One week great fires burn throughout the island, but the next forest resprout with lush growth. This appears to be on a twelve week cycle rotating through the winds of magic.
It isn’t long after the storm before the first invaders arrive on Embermore. Drawn by the power now unleashed they arrive looking to take the island and its shards.