Floating Isles

The Northern Wastes are far from the civilised nations, and events often go unrecorded, save for the campsite tales of the barbarous tribes of men who eke out a living in that harsh and uncaring environment. As legends go, a squall of screaming winds once came wailing south wards from the Realm of Chaos -- roiling clouds of black that discharged flickering blue lightning. So many monsters prowled within the great storm that entire tribes were devoured in a bloody slaughter. Yet contained within the darksome tempest was magical might for the taking, so much power that even the least of the tribal shamans could fell Giants with a glance and smash mountains with bolts of incandescent fury. As rival tribes fought for supremacy, so many spells of titanic proportions were unleashed upon the world that the very ground began to break apart. Such was the fury of the storm that the broken landmasses rose up like inverted mountains, floating high into the air. Even as the hellish clouds dissipated the last gusts sent them scudding southwards, pushed by the wind as is a ship under sail. Whether these strange aerial islands are still adrift, none can say.

Source

 * Storm of Magic (supplement) pg. 8-9