Complex sentence: In the Caucasus however, the situation quickly deteriorated after Maslamah's departure: while al-Djarrah campaigned north of the Caucasus, the Khazars swung behind him and attacked his main base, Ardabil.
Split into simpler sentences: In the Caucasus however, the situation quickly deteriorated after Maslamah's departure. While al-Djarrah campaigned north of the Caucasus, the Khazars swung behind him and attacked his main base, Ardabil.