The March (or Margraviate) of Carniola (Slovene: Kranjska krajina; German: Mark Krain) was a southeastern state of the Holy Roman Empire in the High Middle Ages, the predecessor of the Duchy of Carniola. It corresponded roughly to the central Carniolan region of present-day Slovenia. At the time of its creation, the march served as a frontier defense against the Kingdoms of Hungary and Croatia.

March of Carniola - Wikipedia