The era is called the heyday of Islam, and some call it the Islamic Renaissance. The 9-10. Despite the political turmoil of the 19th century, the economy and trade developed widely. Most of the coins were marked with the name of the mint and the date of minting. The next change was ordered by the Abbasid caliph, al-Mamun (813-833 AD), who unified the monetary system that later survived for many hundreds of years. they kept it until the 19th century, thereby signaling their loyalty to the Abbasid caliphs, the leaders of the Islamic religion.