The Persian Empire
Around 2000 B.C. the Persians left central Asia in search of greener fields for their cattle. They eventually settled on a plateau near the Persian Gulf. Around 545 B.C. the Persians, who had by now developed a powerful military, moved out of their homeland and began to conquer their neighbors. By 525 B.C., Persian armies had conquered a territory that was over 3,000 miles across from border to border. In its day it was the largest empire on Earth.
The Persians were tolerant of the beliefs and cultures of the peoples that they had conquered. They allowed them to continue living their lives in the manner that their cultures dictated. This stood in stark contrast to the Assyrians who had enforced their rule through fear. This tolerance led to the people accepting their Persian conquerors.
Persian Kings ruled by appointing local governors called Satraps. These satraps enforced the laws and decrees of the king. Additionally, the King appointed traveling eyes and ears to make unscheduled visits to the Satraps in order to insure that they remained loyal.
The Persian Empire continued to dominate the area until around 300 B.C. when they were conquered by the Macedonian general Alexander The Great.