Kninska Krajina (English: Knin frontier) is a geographical and historical region in Croatia, part of the larger Zagora (hinterland) region. It is located around the town of Knin.
Kninska Krajina is situated between Bukovica in the southwest, Lika in the northwest, Drniška krajina (in Zagora) in the south, Cetinska krajina in the southwest, and (Završje) Bosnia and Herzegovina in the east.
In the 6th century, the region was settled by Slavs (Sklavenoi). Knin itself was first mentioned by Byzantine Emperor Constantine Porphyrogenitus (r. 913–959) as the centre of a parish under Croatian rule. At the request of King Peter Krešimir IV of Croatia (r. 1058–1075), Knin became an episcopal see. Demetrius Zvonimir of Croatia (r. 1075–1089) was seated in the town. There are remains of Serbian churches and manastires in this region dating from 8th century. This suggest that Serbian people lived here for several centuries .
In the 15th century, the Ottoman Empire occupied the area resulting in most of the native population fleeing the region. It was largely abandoned and devastated as the Ottoman army advanced towards the north and west. The region was administrated into the Sanjak of Kirka.
By the 17th and 18th centuries, the Austrian Empire managed to thwart the Ottoman advances, meanwhile the area had been slowly repopulated by Eastern Orthodox Christian Serbs since at least the 15th century. These Serbs had fled the Ottomans and were given lands in exchange for military service in the so-called Military Frontier (the Austrian-Ottoman buffer zone).