The Fatimid Caliphate came into existence during the age of the 11th Fatimid Imam, Imam Abu Muhammad Abdallah al-Mahdi Billah. Imam al-Mahdi Billah and his two successors, Imam al-Qaim bi-Amr Allah and Imam Abu Tahir Ismail al-Mansur Billah, chose to mint coinage with the Sunni legends (which was common in the newly conquered regions) with only subtle differences from the previous ruling dynasties, albeit with very high gold fineness. The most drastic change to the coinage during the reign of these three Imams was the introduction of the Kufic Arabic script by Imam al-Qaim bi-Amr Allah.
As the Fatimid Caliphate grew stronger, they were able to take advantage of the political chaos in the Ikhshidid dynasty and take over Egypt. When Imam Abu Tamim Ma’ad al-Mu’izz Li-Dinillah moved the capital of the Fatimid Caliphate from Ifriqiya (Northern Africa) to the East to found the city of Cairo (also known as al-Mu’izzayah al-Qahira, or “The Cairo of al-Mu’izz”) in 362 H (963 AD), He brought with him one hundred camels carrying millstone shaped gold bars. In addition to this, the Fatimid Caliphate now also had access to gold from the gold mines of Egypt. This supply of gold was vital to ensure the debased and devalued currency of the Ikhshidids could be reformed with a new currency that would repeat the success and reputation of the currency that the Fatimid Caliphate had introduced in Ifriqiya.
The coinage minted under Imam al-Mu’izz were the first to include the Shia message “wa ‘Ali Afdal al-Wasiyyeen wa Wazir Khayr al-Mursileen” (and Moula Ali is the most excellent of the Wasees and the vizier of the best of the Messengers). Additionally, Imam al-Mu’izz introduced the two and three circular legends and single and double marginal lines with the “bulls-eye” design that the Fatimid currency is known for.
To ensure the newly minted Imam al-Mu’izz coinage were to become prevalent, many administrative policies were introduced. Some policies required that taxes only be paid with the new Fatimid dinaars, while other policies devalued other currencies in circulation such as the Abbasid al-Radi dinaar. Flooding the market with these new dinaars would not mean much if they didn’t hold their high intrinsic value (reportedly reaching highs of 98% fineness for over a century). To ensure the quality of the Fatimid dinaars and dirhams, the mints were supervised by the Chief Qadi al-Qudat (a judge who rules in accordance with Islamic religious law). Some of the tasks of the Chief Qadi al-Qudat, in regards to the minting of the coinage, was to ensure the refining of the metals and the fineness of the alloys used in the dinaars were consistently above-par, the prevention of theft of the gold, silver and other precious metals, and the operation of the mints.
Additionally, as the Fatimid coinage were being spread throughout the kingdom, glass weights were produced which traders could use to weigh dinaars and dirhams being presented as payment for goods. This helped build confidence with the traders that the Fatimid coinage was of superior quality and consistency. The glass weights were produced with similar stringent quality control that the minting of the Fatimid dinaars were known for. Additionally, to ensure the precision of the glass weights and to ensure the traders would accept them as being official, they were manufactured in the Dar al-Iyar (the Bureau of Standards) in the presence of the Muhtasibun (Supervisors of Bazaars and Trade).
Over the years the quality of the dinaars being produced by the Fatimid mints reached such a high that the population of the Caliphate and surrounding areas used to rely on it as being the defacto currency of the region (similar to how the American Dollar is currently considered an international currency), and were rarely even weighed (an act which was unheard of when other currencies of the region were involved). When the Crusaders took over Palestine, they realized their currency was not accepted and they were forced to mint imitation Fatimid dinaars (in the name of Imam Abū Tamīm Ma’add al-Mustanṣir bi-llāh and Imam Manṣūr al-Āmir bi’Aḥkāmi’l-Lāh) to ensure they were able to trade with the inhabitants of the land. The Crusaders saw their inability to mint imitation dinaars with considerable fineness (and legible inscriptions) as an opportunity to devalue the Fatimid currency. These imitation dinaars flooded the region and led the Fatimid Caliphate (now under the rule of Imam al-Amir) to launch an investigation. Concurrently, the Crusaders were able to take control of Syria from the Fatimid Caliphate, and the loss of the mints in Syria resulted in a mint being erected in Cairo for the first time. This mint, al-Dar al-Amiriyya, was built sometime in Shawwal 516 H (December 1122 AD). Imam al-Amir also introduced a new civilian position, Musharif al-Dar al-Darb (the Supervisor of the Mint House) who would work in unison with the Qadi al-Qudat to ensure successful operation of the mints.
The variety of dinaars and dirhams minted by the Fatimid Caliphate is truly staggering. While they might seem similar and unvaried to the untrained eye, the Fatimid Caliphate produced more varied and distinct coinage than any other Islamic dynasty of comparable duration.