Complex sentence: Louis III received the ancient northern partitions of the Merovingian kingdom, Neustria and Austrasia (including Lorraine), and Carloman received the southern partitions, Burgundy and Aquitaine (including Septimania).
Split into simpler sentences: Louis III received the ancient northern partitions of the Merovingian kingdom, Neustria and Austrasia (including the Lorraine). His other son Carloman received the southern partitions, Burgundy and Aquitaine (including Septimania).