Recent excavations show that Jerash was already inhabited during the Bronze Age (3200 BC - 1200 BC). After the Roman conquest in 63 BC, Jerash and the land surrounding it were annexed by the Roman province of Syria, and later joined the Decapolis cities. In AD 90, Jerash was absorbed into the Roman province of Arabia, which included the city of Philadelphia (modern day Amman). The Romans ensured security and peace in this area, which enabled its people to devote their efforts and time to economic development and encouraged civic building activity.

The city finally reached a size of about 800,000 square metres within its walls. The Persian invasion in AD 614 caused the rapid decline of Jerash. However, the city continued to flourish during the Umayyad Period, as shown by recent excavations. In AD 749, a major earthquake destroyed much of Jerash and its surroundings. During the period of the Crusades, some of the monuments were converted to fortresses, including the Temple of Artemis. Small settlements continued in Jerash during the Ayyubid, Mameluk and Ottoman periods. (Wikipedia)