Complex sentence: The two most prominent Norman families to arrive in the Mediterranean were descendants of Tancred of Hauteville and the Drengot family, of whom Rainulf Drengot received the county of Aversa, the first Norman toehold in the south, from Duke Sergius IV of Naples in 1030.
Split into simpler sentences: The two most prominent Norman families to arrive in the Mediterranean were descendants of Tancred of Hauteville and the Drengot family. Then Rainulf Drengot, from the same family, received the county of Aversa from Duke Sergius IV of Naples in 1030.