Numismatics, the study of coinage, is a rapidly expanding part of archaeology that reveals what ancient countries did and how they did it. In our case, numismatic evidence shows the visual history of the first seven decades of Islamic rule.
Muhammad transitioned in 632, and the caliphs who followed him made the Islamic Empire a giant trading market. By nature, Muslims are traders. Muhammad had a trading background, as did several of the "rightly guided" caliphs that followed him. Coinage is an integral part of the infrastructure that promotes trade. The Muslims did not mint coins at first. By Muhammad's death, Muslims were using the gold solidi minted by the Byzantines or the silver drachms minted by the Sasanians (Persians). It was a humiliating experience for the Muslims because the Byzantine coins had Christian symbols, and the Persian coins had Zoroastrian characters.
It took six caliphs about 70 years to come up with the coinage that traders would accept. More importantly, the coinage acted as a recruiting poster for their religion. The gold coins were known as dinars, and the silver coins were called dirhams. That format lasted for the next 1,300 years. Here is the story of their coinage.
The primary role of gold and silver coins was to aid economic and monetary exchanges. If the coinage "looked" right, it was accepted in the market. As long as the degree of fineness of the gold and silver coinage remained constant, the coin's purity was not a factor. In early market transactions, gold was weighed against predetermined weights. However, as coins like Athenian owls and Roman denarii became commonplace, it was not necessary to weigh but to count the number of coins, knowing the coins were consistent in weight. Having to weigh coins to conduct trade was an inconvenience. Counting coins was so much easier.
The Byzantine Solidus
The Byzantines did not mint very many silver coins. Their primary coin was gold, called a solidus or solidi for plural. On the front side of the coin, referred to as the obverse, an image of the emperor alone or with his potential successors (his sons). The reverse side had an apparent Christian symbol as a cross on a stepped platform. Later, they used angels and even an image of Jesus Christ on the reverse side. What emperor would not want to be seen in Christ's company? With inscriptions in Greek, these gold coins were of very high quality, and the standard weight was 4.55 grams, allowing them to be traded by number.
The image above displays a Byzantine solidus with the Emperor Heraclius in the center, his son Heraclius Constantine on the left, and his other son Heraclonas on the right. It weighs 4.25 grams and was minted sometime between 632 and 641. I copied these coins a little larger than the actual ones so that you could see the design details. These are the coins that the Muslims initially tried to imitate.
The Sasanian (Persian) Drachm
In the Sasanian world, which included parts of Iraq, Iran, and Central Asia, the dominant coinage was the silver drachm. The obverse had an image of the ruling emperor with an elaborate crown, while the reverse included a fire altar with an attendant on each side. The fire altar was a symbol of the Zoroastrian religion. Inscriptions on the obverse had the emperor's name and appropriate titles. The reverse side listed the mint and the regnal date. The Sasanian drachm was not as high quality as the Byzantine solidus. The drachm's standard weight was 4.2 grams but varied from 3.6 to 4.3 grams. This coin was traded by weight, not by number, although the purity of the silver was consistent.
The drachm above shows the type of coin that the Persians were using. This particular coin was minted from 420 to 438 during the reign of Varhran V.
Attempts to Mint a Coin
The first attempts by Muslims to mint their coins came in 651, just 19 years after Muhammad's death. The Muslim empire had just captured Persia, and with the Persian mint in hand, the third caliph, Uthman, used the Sasanian format. Initially, he even used the image of the last Sassanid ruler on the obverse, but on the reverse, he added short phrases in Arabic, such as "In the Name of God." The new coinage looked so much like the earlier coinage in size, weight range, and overall appearance that it would have been no apparent problem to substitute one for the other. Inscriptions may have varied with different dates, mints, the names of different Muslim governors written in Pahlavi (Persian), and a limited range of short Arabic phrases. Still, the coins were useful for 40 years.
The attempts to mint a gold coin were more elusive. The fifth caliph, Mu'awiya, who reigned in Syria (661-680), minted some silver dirhams in the Sasanian style and some dinars in the Byzantine style. In the first year of his rule, he aimed to mint a gold coin similar to the Byzantine solidus. He took the design of the Byzantine solidus pictured previously and removed the three crosses carried by the emperor and his two sons on the obverse side. On the reverse side, he cleared the crossbar on the cross on the platform so that it was just an elongated "T." The Greek lettering was left as it is, with the outcome of the coin looking like a cheap forgery. People refused to accept the coin, which failed as a medium of exchange. Consequently, for the next three decades, the Muslims floundered about to develop a standard gold coin capable of being the empire's reserve currency.
Mu'awiya's nephew, al-Malik, became the sixth caliph (685-705) after Muhammad's death to run the empire. Al-Malik continued the policy of mimicking Byzantine designs with Islamic characters. Coins minted in 691 now had on the reverse the Islamic affirmation of faith: "In the name of God, there is no deity but God; He is One; Muhammad is the messenger of God." Muslims were incensed that Christians believed in the Trinity, and this was their way to strike back. Consequently, the Byzantine emperor refused to accept the Islamic gold currency, and a new conflict between the Byzantines and the Muslims ensued.
In 697, the caliph abandoned all traces of iconography and introduced the first Islamic coin devoid of figurative representation. On both sides of the new dinar were inscribed verses from the Qur'an expressing the message of Islam and making each coin an individual missionary of the faith. The dirham was revamped as well. The new coins were propaganda for a new religion. Quranic verses used on the coins included 9:33, 9:112, 48:28, or 61:9. After introducing this coin, al-Malik issued a decree making it the only currency allowed throughout Islamic territory. Those who did not comply faced the death penalty.
The coin above was minted in 707 by al-Maliks son, al-Walid 1. While the standard weight is 4.25 grams, this dinar is 4.2 grams.
The new gold dinars weighed a bit less than the solidus. The standard weight of the solidus was 4.55 grams, while the dinar was 4.25 grams. This coinage was minted with less gold for a purpose. The old saying "Bad money drives out good money" is sometimes called Gresham's Law, although there is no evidence that Thomas Gresham (d. 1579) had anything to do with it. The new dinar had fewer grams of gold but was used to replace the solidus. People did not want to use their solidi, which had more gold, if a dinar having less gold would make the same purchase. The dinar was overvalued, but if they had to use it, they hid away their solidi in response. Al-Malik had achieved his goal of driving out the Byzantine coinage and replacing it with his dinar.
Gresham's Law did not apply to the silver coinage because the Islamic silver dirhams were the same weight as the earlier Sasanian drachms.
Al-Malik, the sixth caliph of Islam, not only minted a coin without images but, for the first time, inscribed Qur'anic verses on it. The caliph was using the Muslim sacred text to legitimize his message of the triumph of Islam but in a far more public way than had been done before. Anyone who held the new all-epigraphic coinage and wished to know what was inscribed would learn that they were holding God's word as revealed in Arabic to the Prophet Muhammad.