Complex sentence: For all his energy, Maslama's campaigning failed to produce the desired results: by 729, the Arabs had lost control of northeastern Transcaucasia and been thrust again into the defensive, with al-Jarrah again having to defend Azerbaijan against a Khazar invasion.
Split into simpler sentences: For all his energy, Maslama's campaigning failed to produce the desired results. By 729, the Arabs had lost control of northeastern Transcaucasia and been thrust again into the defensive, with al-Jarrah again having to defend Azerbaijan against a Khazar invasion.