The Great Collapse

The Great Collapse was the result of the War of Collapse, which caused the complete downfall of the three major kingdoms occupying the New Hudson area. The turmoil between the kingdoms of Brightburn and Festwich had been brewing for hundreds of years. Both wanted control over the lake trading routes and the trade with the southern areas. The kingdom of Frostborne desperately tried to stay out of the conflict for years, but eventually was forced to pick a side, and they chose the Festwich kingdom. After a reconnaissance mission into the Springkeep castle by the Frostborne Rogues was intercepted, the War of Collapse began.
The Great Collapse is the current metric used for era separation, events prior to the Great Collapse are labeled as B.C. or Before Collapse, and all events happening after labeled P.C. or Post-Collapse. 

The War of Collapse

The Brightburn kingdom struck first, raiding a number of the Festwich and Frostborn farming villages and burning nearly half their crops. The Brightburns continued to limit the food supplies to the other kingdoms, and intercept their trade routes whenever possible. The Frostborne Keep was besieged by the Brightburns, and was overtaken. The Frostborne knew about the plans for the siege, and were promised help by the Festwich that never arrived. The Festwich, however, had sent their own troops to Springkeep while they raided the Frostborne, to take the city. Now scrambling to attack each other and hold their captured kingdoms, the leadership of the armies fought to make choices and choose battles. After nearly a year of fighting, all the side's numbers dwindled and their vassal towns were all abandoned. All the surviving troops and leaders fled the land in fear and shame, leaving the remaining commoners to flee or survive unprotected.