"In the late Bronze Age, the Neolithic population was replaced by more warlike Indo-European tribes known as the Illyrians. Celtic migrations in the 4th and 3rd century BCE displaced many Illyrian tribes from their former lands, but some Celtic and Illyrian tribes mixed.... Conflict between the Illyrians and Romans started in 229 BCE, but Rome wouldn't complete its annexation of the region until 9 CE. In the Roman period, Latin-speaking settlers from all over the Roman empire settled among the Illyrians and Roman soldiers were encouraged to retire in the region."
In what is now called Bosnia and Herzegovina, today's "History of" county.