Sort of true, sort of not?
Greyhawk and Birthright are both settings with pretty much ongoing conflict between states/regions/peoples throughout the history of those lands (e.g., in Greyhawk, the March of Bissel - which is the gateway between east and west - has long been contested ground between Ket to the west, Gran March/Keoland to the south, and Veluna/Furyondy to the east; likewise, the lands of the Great Kingdom of Aerdy have a long and tumultuous history).
That said, while I probably wouldn't make either of those settings the origin world for Barovia, a continent other than Cerilia in the Birthright setting arguably could fit the bill.