Complex sentence: In 1220, Charikar was the site of the battle of Pirvan, where Jalal ud-Din delayed the invading Mongol army, which allowed him and part of his army to escape the fall of the Khwarezmid Empire.
Split into simpler sentences: In 1220, Charikar was the site of the battle of Pirvan, in which Jalal ud-Din delayed the invading Mongol army. This allowed him and part of his army to escape the consequences of the fall of the Khwarezmid Empire.