The World is shattered.
Civil war and rebellion springs up across the land. To the south Lordel, a former bastion of safety and justice, has been thrown into turmoil as the Undead decimate the land. The Mages of the Tower have preformed an ancient ritual, shattering the borders between Thaur and the Astral Sea. As reality is torn to shreds, the Northern Kingdoms fight against the Calaidian Empire from the West.
As the sky is hidden behind the smoke of burning towns, and the kingdoms are paid for in blood, Thaur will be reborn from the ashes of chaos. For when it comes time for the Dance of Dragons, only fools get caught willingly in the middle.

After that, take a look at your wiki. There is some more helpful info there.

A Dance with Dragons