|The most important centers of learning in the ancient world were located in Greece, Egypt, Syria, Mesopotamia, Iran, India and China. In Greece, before the establishment of the Academy in Athens, there arose mathematicians such as Thales and Pythagoras, and physicians such as Hippocrates, though it seems unlikely that their progress in science was uninfluenced by the works of others, especially as regards their mathematical advancement. A part of their received knowledge must have had its roots in Egypt and Babylonia, though the mechanism of its transmission is yet to be uncovered. In the 3rd century BC, the Academy in Athens entered into a period of decline and was gradually superseded by its rival in Alexandria.
In the 3rd and 2nd centuries BC the Alexandrian school embarked on its most productive phase and continued to flourish well into the 4th century AD. Such great scientists as Euclid, Apollonius, Archimedes and Ptolemy received their training in Alexandria. In the aftermath of the ascendancy of Christians, scientific research was seriously curtailed and teaching, apart from subjects dealing with the church dogma, was confined to medicine. The advent of Islamic period witnessed the migration of a large group of Alexandrian teachers and students to Antioch.
The school of Edessa, or al-Ruha, was the center of translation of Greek works into Syriac, as well as a major seat of learning for some four hundred years, starting from the 2nd century AD. The school of Edessa was finally closed by the emperor Zeno in 489 AD, and many of its teachers and students moved to Jundishapur. The closure of the Athenian Academy in 593, at the order of Justinian, brought a new wave of migrating scholars to Jundishapur (or Gondeshapur), as well as to Harran (the Roman Carrhae).
Toward the end of the 6th century AD, the famous Iranian physician Burzoe brought back a group of his colleagues along with several medical works upon his return from India.
The school of Jundishapur was established in the 6th century AD and soon turned into a major center for translation of Greek works into Pahlavi, as well as a seat of medical education in Aramaic. A group of Greek physicians was invited to Iran and the city became home to a major hospital. Jundishapur was spared the damage wrought by the Muslim conquests, thanks to the wise and farsighted actions of its citizens, and remained a hub of scientific activity. Some of the greatest pioneers of Islamic medicine began their careers in Jundishapur.
In addition, in the later part of the Sasanid period, there existed schools of mathematics and medicine in Marv, Balkh and Sa`d, which continued to flourish a long while after the advent of Islam.