Abbasid Dirham

The Abbasid dirham was the silver coin of the Abbasid Caliphate, the dynasty that replaced the Umayyads in 750 CE and ruled from Iraq. It continued the epigraphic silver dirham created by the Umayyad reform of AH 79 (698–699 CE): a thin, broad coin of about 2.9 g bearing Arabic religious inscriptions, the mint name and the date, and no images.

Struck at dozens of mints, the dirham was the everyday medium of exchange of the caliphate for more than a century and a half. It also travelled far beyond the caliph's borders, and hundreds of thousands of specimens have been recovered from Viking-age hoards around the Baltic.

The word dirham comes, through Middle Persian, from the Greek drachma. Its broad, thin form was inherited from the Sasanian drachm, which Arab governors had continued to strike after the conquest of Iran. The reformed dirham had a theoretical weight of about 2.97 g, conventionally seven-tenths of the mithqal on which the gold Umayyad dinar was based, although actual weights of individual coins varied.

Together with the gold dinar and copper fals, the dirham formed a three-metal system. The rate between dinar and dirham was not fixed for long; it moved with the relative supply of gold and silver, a recurring problem of bimetallic systems.

The Abbasids kept the Umayyad layout but changed some of the texts. Most notably, the reverse field replaced the passage from Sura 112 with the statement that Muhammad is the messenger of God. From the later 8th century the names of governors, officials and designated heirs were often added, which makes many dirhams useful evidence for administrative history.

Under al-Ma'mun in the early 9th century the design was standardised, with a second marginal legend containing a Qur'anic verse, and this format was used across the caliphate's mints for the rest of the classical period.

Dirhams were struck at a very large number of mints. Among the most productive were Madinat al-Salam (Baghdad, founded 762), al-Basra, Wasit and al-Kufa in Iraq, al-Muhammadiyya (Rayy) in Iran, and eastern mints such as Balkh, Samarqand and al-Shash. Mines in Central Asia and the Hindu Kush, including the Panjshir valley, supplied much of the silver. By the late 9th century the Samanid rulers of Transoxiana, who nominally recognised the caliph, were among the largest producers of dirhams.

From the 10th century political fragmentation, falling silver output and debasement in several regions reduced the dirham's role, and in parts of the Middle East good silver coin became scarce during the 11th and 12th centuries, a period sometimes called the silver famine. The caliphate continued to strike coins in Baghdad until the Mongol sack of 1258.

From the late 8th century, dirhams flowed north through the Caucasus and Central Asia to the middle Volga, where Bulgar and Khazar traders exchanged them for furs, slaves and other goods brought by Scandinavian and Slavic merchants. The flow peaked in the 10th century, when most coins reaching the north were Samanid.

Hoards of dirhams are known from European Russia, the Baltic lands, mainland Sweden and above all the island of Gotland. The Spillings hoard, found on Gotland in 1999, contained more than 14,000 coins, almost all Islamic. In these economies silver was valued by weight rather than by count: coins were often cut into pieces, tested with small nicks and weighed alongside hacked jewellery. The supply of dirhams declined sharply around the end of the 10th century, after which German and Anglo-Saxon coins, including the English penny, became the main silver arriving in Scandinavia.

The dirham remained a unit of weight and a reference coin in Islamic law, where the threshold for zakat on silver is expressed as two hundred dirhams. The name survives in modern currencies such as the Moroccan dirham and the United Arab Emirates dirham, and the coin remains one of the most widely studied in early medieval long-distance trade.

• British Museum – Collection online
• American Numismatic Society
• Encyclopaedia Britannica – Dirham