Complex sentence: Alessandro Dudan was born in Vrlika, a small town in inland Dalmatia, Croatia, which later became a part of Kingdom of Dalmatia, an administrative division (kingdom) within Austro-Hungarian Empire.
Split into simpler sentences: Alessandro Dudan was born in Vrlika, a small town in inland Dalmatia, Croatia. Then it was a part of Kingdom of Dalmatia, an administrative division (kingdom) within Austro-Hungarian Empire.