Croatian Military Frontier

The Croatian Military Frontier (Croatian: Hrvatska vojna krajina or Hrvatska vojna granica) was a district of the Military Frontier, a territory in the Habsburg monarchy, first during the period of the Austrian Empire and then during Austria-Hungary. == History == Founded in the late 16th century out of lands of the Habsburg Kingdom of Croatia, it was initially a nominal part of that Kingdom, to be transferred in 1627 to direct imperial rule as part of the Military Frontier.

Source: Wikipedia — Croatian Military Frontier (CC BY-SA 4.0)