Archaeological research conducted in Banja Luka region and its surroundings speak of the existence of settlements in this region in the far past.
The oldest human traces in this region date back to the Paleolithic era or the Old Stone Age which lasted since the creation of man until 10,000 BC.
“Paleolithic man is the first man to inhabit the Banja Luka region. Some of his traces were found at the Kastel fortress, more precisely some of his flint tools and instruments. Lot of objects from Neolithic, Bronze Age and Ancient Times were also found at Kastel,” said the archaeologist of the Museum of Republika Srpska Goran Simonović.
There are lots of traces of Romans in the Banja Luka region as well, including roads, settlements, facilities, money, etc.
Romans were the first to discover the medical effect of mineral waters at the sources in the Banja Luka region, Gornji Šeher, Slatina and Laktaši. Namely, in the ancient times Banja Luka was situated on a significant road constructed by the Romans, which led from Split to Gradiška. Thus, there is a high possibility that there was once a municipality there, i.e. settlement of higher level, a town. This is evidenced by numerous archaeological findings at Kastel and other locations.
Numerous archaeological sites and significant remains of forts in the canyon of Vrbas also testify to the medieval life of Banja Luka, such as the medieval town Greben, fort Bočac and town Zvečaj at the territory north from the present city in Lijevče Polje and Potkozarje, as well as numerous charters and writings issued in the towns of Vrbaska and Zemljanička parishes.
The name Banja Luka is mentioned for the first time in 1494, when in the charter addressed to local commanders the Croatian-Hungarian king Vladislav II Jagelonac stated the name of Juraj Mikulašić as the castellan of Banja Luka.