Complex sentence: The second Mongol invasion of the Caucasus started with the expedition of Chormaqan against Jalal ad-Din Mingburnu, ordered by khan Ögedei in 1231, southern Persian dynasties in Fars and Kerman voluntarily submitted to the Mongols and agreed to pay tributes.
Split into simpler sentences: The second Mongol invasion of the Caucasus started with the expedition of Chormaqan against Jalal ad-Din Mingburnu, ordered by khan Ögedei in 1231. The Southern Persian dynasties in Fars and Kerman voluntarily submitted to the Mongols and agreed to pay tributes.