Banja Luka's history dates back to ancient times. There is substantial evidence of a Roman presence in the region during the first few centuries AD, including an old fort in the center of the city. The area of Banja Luka was wholly in the Roman province of Illyricum, lying on important Roman roads between Dalmatia and Pannonia.
Slavs settled the area in the 7th century AD, although the exact nature of their migrations remains something of a mystery. What is known is that the first mention of the city dates to 1494, by Vladislav II. The origins of the name are debated to this day. Banja means "Bath", perhaps a reference to the mineral springs in the region, and Luka means port which could be because of the city's location on the Vrbas river.
During Ottoman rule, Banja Luka grew significantly in terms of importance. For a while, it was the seat of the Bosnian pashaluk, and the lords of the region built a variety of impressive structures that would make up the core of the city's old town. In 1688 the city was set to the torch by an Austrian army. For all its good to the region however, Banja Luka as a city wasn't modernized until rule by Austria-Hungary in the late 19th century.
Austrian occupation brought westernization to Banja Luka. Railroads, schools, factories, and infrastructure appeared and was developed. This led to a modern city of great importance, that after World War I became the center of the Vrbas province of the 1st Yugoslavia. During World War II, Banja Luka would be occupied by the Croatian Ustasha regime. It was liberated on April 22nd, 1945.
Socialism & Yugoslavia
Aside from a devastating earthquake in 1969, Banja Luka's time in Yugoslavia was extremely beneficial. The city became far more urbanized as its population grew five fold. In the final years of the socialist Yugoslavia, Banja Luka's population was 150,000.
After the Tito era of 1948, Yugoslavs enjoyed many freedoms and were even allowed to travel out of the region and work in the West.