In 550 B.C. Cyrus the Great founded the Persian Empire, which went on to conquer and rule the fertile crescent, Asia Minor, and Egypt for the next two hundred years. In the fourth century B.C. Alexander the Great conquered all of the lands ruled by the Persian Empire, including parts of Thrace, Asia Minor, Egypt, Palestine, Syria, Mesopotamia, Armenia, and the Persian plateau. After Alexander’s death Persia came under the control of the Hellenistic Seleucid Kingdom.
The Seleucid Kingdom was spread out, and was plagued by rebellion and civil war. By the first century B.C., as Rome’s power was rising in the west, the Seleucids had lost control of all lands east of the Euphrates River to the Parthians of northeastern Persia, who had successfully rebelled against them a century earlier.
Rome and the Kingdom of Parthia fought numerous bitter wars for control of western Asia. The Parthians occasionally mounted serious challenges to Roman rule in the western Mediterranean, invading Syria and threatening Asia Minor and Palestine, but never successfully established permanent outposts west of the Euphrates. At its height, Rome held sway over the kingdom of Armenia and the “Land between the Rivers,” Mesopotamia, but was never able to subdue the Parthians on their home turf in the mountains of Persia.
In 224 A.D., the Parthian Empire was overthrown by Ardashir I, King of Persia and became the Sassanid Empire. After the fall of Rome, the Sassanids and Byzantium, the Eastern Roman Empire, continued to fight increasingly bloody wars, draining the resources of both empires to near exhaustion. Peace was finally restored to the region when a new power, the Islamic Caliphs of Arabia, swept aside the Sassanids and Byzantines alike, conquering all of the Middle East and North Africa in the 7th century.