Complex sentence: His father, Antonio, was one of the richest landowners of Dalmatia and his mother, Caterina Gazzara, belonged to one of the most important families of the Italian community of Split.
Split into simpler sentences: His father, Antonio, was one of the richest landowners of Dalmatia. His mother, Caterina Gazzara, belonged to one of the most important families of the Italian community of Split.