The landscape region is almost exactly the same as the county. Its tradition goes back into the undocumented iron age and [viking age]? prehistory, when this region had its own king and law. The region kept its own laws (Östgötalagen) into the medieval times when Sweden was a united kingdom. Traditionally, the region is divided into two halfs, east and west of the river Stångån?, which flows from the south into lake Roxen at Linköping.