Complex sentence: Early Muslim armies stayed in encampments away from cities because Umar feared that they may get attracted to wealth and luxury, moving away from the worship of God, accumulating wealth and establishing dynasties.
Split into simpler sentences: Early Muslim armies stayed in encampments away from cities because Umar feared that they may get attracted to wealth and luxury. In the process, they may get away from the worship of God and become attracted to wealth and start accumulating wealth and establishing dynasties.