Bosanska Krajina is in Bosnia and Herzegovina.
Roughly a triangle bordered by Croatia to the north and west, Central Bosnia to the southeast, and Northeastern Bosnia to the east, Bosanska Krajina is the northwestern part of the country. The name of the province, meaning the "Bosnian Frontier" in all of the local languages (Bosnian, Croatian, and Serbian; Serbian Cyrillic: Босанска Крајина) as well as in other Slavic ones, is a legacy of the rivalry between the Austrian and the Ottoman Empire, as the region was for long the borderland between these two major powers of the past.
Roughly divided politically in half, the western half of Bosanska Krajina forms part of the Bosniak/Croat-majority Federation, while the eastern half forms part of Republic of Srpska. Most of the formerly multi-ethnic towns of the region are now (since the Yugoslav Wars of 1992–1995) dominated by a single ethnicity, depending on which side of the inter-entity border they fall on.
All three languages of the region (Bosnian, Croatian, and Serbian) are mutually intelligible with each other, however while in Republic of Srpska, you may need to decrypt some Cyrillic.
Ride-sharing in the region is in 2012 often done through the Trazim- nudim prevoz (Searching- offering transport) Facebook group.