Complex sentence: Neum is a town of 2,000 citizens (1991 census) and the area around the city is rich with historical and archeological remains of the Illyrians, a people who lived in the Balkans for many thousands of years.
Split into simpler sentences: Neum is a town of 2,000 citizens (1991 census) and the area around the city is rich with historical and archeological remains after the Illyrians. The Illyrians were a people who lived in the Balkans for many thousands of years.