Complex sentence: Battle of Qarteen was a minor battle between the Ghassanid Arab allies of Byzantine empire and Rashidun Caliphate army it was fought after Khalid ibn Walid conquered Tadmur in Syria, his army marched to Qaryatain, the inhabitants of which resisted the Muslims.
Split into simpler sentences: Battle of Qarteen was a minor battle between the Ghassanid, Arab allies of the Byzantine empire, and the Rashidun Caliphate army. His army marched to Qaryatain, the inhabitants of which resisted the Muslims.