The Krajina in the Balkans is mostly associated with the Military Frontier (Militär Gränze) which acted as the Austrian cordon sanitaire against the Turks in the Middle Ages. The border areas were divided into the following military districts:

• Banat Krajina (on the Serbian-Romanian border)
• Slavonian Krajina (on the Serbian-Croatian border)
• Croatian Krajina (on the Croatian-Bosnian border)

After Croatia declared independence in 1991, the Serb-inhabited parts of the Slavonian and Croatian Krajina organized into Serb Autonomous Regions (SAOs) and finally established the Republic of Serbian Krajina (RSK) in December 1991. Around 150,000 — 200,000 Serbs lived in the RSK. Almost the entire Croatian population of the region was expelled or fled in a campaign of "ethnic cleansing" for which the Krajina Serb leader, Milan Babic, was convicted by the International Criminal Tribunal for the former Yugoslavia in January 2004.

The RSK lasted until 1995 when Croatian forces in May retook western Slavonia in Operation Flash, and in August overran the rest in Operation Storm. As a consequence, almost the entire Serbian population fled in a combination of an evacuation ordered by the Krajina Serb authorities and, allegedly, "a large-scale deportation and/or displacement" conducted by Croatian forces under the command of Colonel General Ante Gotovina (for which the latter has been indicted by the ICTY) [1]. Some Serbs and most of the expelled Croats have since returned, but the Krajina Serb population is still only a fraction of its pre-1995 numbers.