The Parthian and Sassanid Eras
The second Persian empire began to be formed in 248 B.C. and lasted until the coming of the Muslims in 641 A.D. For almost 500 years it was ruled by the Parthians, a Scythian people who had settled in what is now Khurasan. The Parthians freed themselves of Seleucid rule and expanded their control to all the old Persian empire as far west as the Euphrates River. Beginning in the first century B.C. there were frequent clashes between the Persian and Roman empires. In 115–16 A.D. Roman armies advanced to the Tigris, but they were soon withdrawn.
In 226 A.D. the Parthian line was overthrown by Ardashir, the ruler of Persis province, who founded the Sassanid dynasty. The Sassanids were energetic and aggressive. They invaded Syria, and captured the Roman emperor Valerian (260). In 363 the Roman emperor Julian was killed fighting the Persians.
Later aggressions brought the Persians into conflict with the Byzantine Empire. The most illustrious of the Sassanids, Khosrau I (reigned 531–79), forced a humiliating treaty on the emperor Justinian, and then broke it by invading Syria and capturing Antioch. His grandson Khosrau II (590–628) took Damascus and Jerusalem, subjected Egypt, and marched through Asia Minor to Chalcedon across the straits from Constantinople (611–17). The Byzantines soon regained the territory. The constant warfare left both empires unable to meet the Muslim onslaught that began in the 630's.
Throughout the Parthian and Sassanid period there were frequent contacts with Western culture. Christianity was introduced into Persia at an early date and was alternately tolerated and persecuted. In the third century A.D. Manichaeism, a religion combining elements of Christianity and Zoroastrianism, gained a large number of adherents. Later the East Syrian, or Nestorian, branch of the Christian church won a following in Persia.
The official language of the period was Pahlavi, Old Persian written in Aramaic characters. Under the Sassanids the Hellenistic literary influence vanished and Pahlavi literature reached a high point of development. Philosophy and medicine also flourished.
