Even today large parts of the region are swamps, such as the natural reservation Kopački Rit in its southeast.
Another theory states that the name of the region comes from the Croatian and Hungarian word 'bárány', which means ram of 'ovis'.
Croats moved from Bosnia into Slavonia and Baranja en masse after the Ottoman retreat, and this population is today known as the Šokci.
For a short time (in 1918–1919), Baranya was part of Banat, Bačka and Baranja region, which was governed by the People's Administration from Novi Sad.
By the Treaty of Trianon (part of the Versailles peace) in 1920, the Baranya region was formally divided between Hungary and the Yugoslavia, but de facto remained under the administration of the latter until 1921.
On 21–25 August 1921, the Republic was abolished and its territory was included into Hungary, as was previously decided by the Treaty of Trianon.
In 1944–1945, Yugoslav Baranya was part of the Autonomous Province of Vojvodina, while in 1945 it was assigned to the People's Republic of Croatia.
During the Croatian War of Independence in 1991 it came under the control of the self-proclaimed SAO Eastern Slavonia, Baranja and Western Srem, which became part of the unrecognized self-declared Republic of Serbian Krajina.
Most of the municipalities in Croatian Baranja have a Croat ethnic majority with a small Danube Swabians minority.