Complex sentence: Abu'l-Aghlab avenged himself by launching naval raids against Pantelleria and other localities, beheading the Christians taken captive, while a Muslim cavalry raid reached the eastern parts of the island around Mount Etna, burning the villages and crops and taking captives.
Split into simpler sentences: Abu'l-Aghlab avenged himself by launching naval raids against Pantelleria and other localities, beheading the Christians taken prisoner. At the same time, a Muslim cavalry raid reached the eastern parts of the island around Mount Etna, burning the villages and crops and taking captives.