Complex sentence: These warriors were reported to be very skilled in warfare, and though they were not under the direct control of either empire, they acted as a supporting force for neighboring Muslim kingdoms during times of reprisal against Abyssinia.
Split into simpler sentences: These warriors were reported to be very skilled in warfare. Although they were not under the direct control of either empire, they acted as a supporting force for neighboring Muslim kingdoms during times of reprisal against Abyssinia.