The war between Order and Chaos had been ongoing for 10,000 years, and the clash of powers in the shattered Carrow left many ruins. Many of the ruins were finally annihilated through the passing of time and constant clashes. However, ruins that still had powers within them, and much more recent ruins were still discoverable. These ruins ranged from the magic caverns within each kingdom of Order, and also included former human settlements within the realms of Chaos.
Aside from those protected by holy powers or holy sanctuaries within the realm of Chaos (like the Cassouin Temple Complex), most of the ruins on the wilderness is pretty much less than three centuries old. Anything older had already been reduced to dust by the chaotic onslaught.