In the early 10th century the province of Gacka belonged to the first historically known, Banovina of Croatia.
Francia, the European super-power of the time, referred to Borna as dux Guduscanorum, dux Dalmatiae atque Liburniae – the Duke of the people of Gacka, Dalmatia and Liburnia. It is considered that the area which Gacka covered back in the day was much wider than the one at the present, stretching from the Raša River in Istria all the way to the Una River in the east. In a later period, Gacka gradually lost its territories thus narrowing down in size to the present time area. In the mid-10th century, the Byzantine Emperor, writer and philosopher Constantine VII Porphyrogenitus mentions the Croatian counties. Three of them, among the others, stood out as different. Those counties were Gacka, Lika and Krbava. What made them different was the fact that they were ruled by a Ban, while the other counties were ruled by a Duke. In the early 10th century the province of Gacka belonged to the first historically known, Banovina of Croatia.