To quote RftLW
The Last War was a bitter struggle that forever changed the shape of Khorvaire. It was a century marked by shifting alliances, with years of stalemate interspersed with periods of intense battles. This grueling conflict left deep scars on the land and the people, but there was worse to come. On 20 Olarune 994 YK, the nation of Cyre was consumed in a magical cataclysm now known as the Mourning. The cause of the Mourning remains unknown; many fear it was caused by unbridled use of war magic. Shock and fear brought the nations to the negotiating table, and the Last War came to an end in 996 YK with the Treaty of Thronehold.
