Yibalm was created by Gnomes around the beginning of recorded history, in their two hundred year long war against the Cloud Titans (malevolent storm spirits, worshipped by early Humans and Elves as gods which needed to be appeased through sacrifice) and their mortal underlings, in order to take advantage of the vast resources underneath the island and to act as a final stronghold should the Gnomes mainland fortresses fall. Yibalm stood strong throughout the war, and while the Gnomes were never forced to retreat there, it was attacked several times but never taken. The island was abandoned about fourty years after the wars end, but stockpiled with supplies incase of another war.
Another war of that same scale never came, and so Yibalm simply became a name in a few mouldering history scrolls. The fortress island was found again some three hundred years ago by Dark Elven sailors, and recolonised as both a city and a naval base. The seas around south western Molthenan were ruled by Dark Elf pirates and battleships for the best part of fifty years, and many coastal cities fell to them during that time. However, a combination of Gnomish traps, guarding the largest stockpiles in the fortress, and monters which had found their ways into the mines whittled away at the Dark Elf forces from the inside and made them dependant on imports from their mainland cities. The nations of Molthenan had no idea where the Dark Elven armies were coming from, but after careful study of where Dark Elf cargo ships were sailing to and from, they managed to pinpoint the general location of Yibalm. After that, several well timed attacks and blockades on cargo ships meant that the fortress stopped recieving supplies; the Dark Elf armada weakened without new ships and repairs, the populace of the island slowly starved, and after about half of the colonials died off, the remaining Dark Elves on the island surrended and left Yibalm.
After the Dark Elves abandoned it, the human nation Torlenfal forced information about it out of several Dark Elf sailors in return for their lives, and sailed to Yibalm. Wary of the traps and monsters filling the fortress, aswell as several more recent Dark Elf traps, Torlenfal never explored the whole fortress, but started using a small part of it as a high security jail for criminals throughout the world.
The rest of Yibalm is left unexplored, and simply sits there until it is repopulated once more.