Gerasa was inhabited inhabited during the Bronze Age (3200 BC - 1200 BC). However Greeks used to believe that Gerasa was founded by Alexander the Great. Romans annexeted the city and surroundings to the Province Syria.
See:
- http://www.art-and-archaeology.com/jordan/jerash/jerash.html
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Title page THE JARASH CITY WALLS PROJECT. EXCAVATIONS 2001 -2003: FINAL REPORT (With a summary report of The Jerash City Wall Excavation 2000: JCW00. Tr/Wall 2000. By Ina Kehrberg-Ostrasz https://www.academia.edu/38576762/Title_page_THE_JARASH_CITY_WALLS_PROJECT._EXCAVATIONS_2001_-2003_FINAL_REPORT_With_a_summary_report_of_The_Jerash_City_Wall_Excavation_2000_JCW00._Tr_Wall_2000
- Antioch on the Chrysorrhoas, Formerly Called Gerasa. Perspectives on Biographies of a Place - Achim Lichtenberger https://www.academia.edu/44526007/Antioch_on_the_Chrysorrhoas_Formerly_Called_Gerasa_Perspectives_on_Biographies_of_a_Place