Kilwa coins are a type of currency primarily minted in the southern part of the East African coast, most especially within the Swahili culture capital of Kilwa Kisiwani, between the 11th and 15th centuries AD.
These coins were made primarily of copper, but with a few examples of bronze, gold and silver. They were created by smelting the metal and pouring it into molds, and in this manner imprinting the coins with the names of the sultans who presumably requested their production. The coins are useful in a number of traditional numismatic ways, but unfortunately, the coins do not bear dates: rough chronologies have been established based on excavated examples and what is known of the sultans from the Kilwa Chronicles.
Kilwa coins have been found at archaeological sites throughout the east coast of Africa: thousands of them have been found at Kilwa, most of which are of copper. Other sites which have included Kilwa coins are Songo Mrana, located a few miles away from Kilwa in Tanzania, and Shanga on the northern coast of Kenya. Shanga's mint was most vigorously operating in the 8th and 9th centuries AD; a mint at Tumbatu on Zanzibar from the 11th-13th centuries.
As is typical with Islamic coinage, the same Kilwa coins were minted in a variety of metals. The vast majority of Kilwa coins are made of copper, although there are smaller known assemblages of bronze, silver and gold. The metals appear to be regional in distribution: copper is prevalent in the Kilwa region, silver is most often found along the coastal corridor and gold was used for international exchanges.
Most of the sphere dominated by Kilwa dynasties used copper, although a few silver coins were found at Kilwa, Kisimani Mafia and Mtambwe Mkuu along the coast. Over 2,000 silver coins were found at Mtambwe Mkuu.
Gold coins are rarely found, and seem to be associated primarily with the sultan al-Hasn ibn Sulaiman, and are decorated with his nickname, "the Father of Gifts". The weight of the gold coins roughly approximates that of the standard Indian Ocean currency at the time, the dinar, supporting the interpretation of gold currency as international in flavor.
Although it is clear that Kilwa coins are firmly part of the period's internationally recognized Islamic coinage, Kilwa coins were locally minted and served the needs of the local populations. The lack of a readily identifiable valuation of the silver and copper coins suggests to some authors that the coins had a more symbolic or social value, rather than simply currency.
Currency and Social Valuation
That the coins were used as currency is undeniable: many of the coins recovered from domestic contexts at Songo Mnara have been cut into halves or quarters. Clipped coins were found in abundance in non-elite contexts at the town, but also occasionally found in elite houses and tombs as well. Coins cut into halves or quarters suggests that the value of a coin could be divided.
Wynne-Jones and Fleisher have also argued that the contexts of copper coins found at Songo Mnara, their variable weight, and the fact that the coins are frequently pierced, suggests a social, rather than (or in addition to) the monetary meaning of the Kilwa coins.
Analytical Use of Kilwa Coins
Archaeologists have interpreted the coins in a number of ways. Coinage is often seen as a reflection of an economy which has become commodified. The presence of Kilwa coins in towns along the Swahili Coast are thought by some scholars to represent evidence of the integration into the trading network of the Indian Ocean, and/or as an indication of the level of integration of the towns into the wider world.
Social information and coastal histories have been gleaned from the coins: some (e.g. Horton and Middleton, described in Wynne-Jones and Fleisher 2012) have reconstructed familial relationships between rulers in the island towns between AD 1000 and 1200. These early rulers' names include "ibn", an Arabic word meaning "son of", and scholars have used that to reconstruct Shirazi tradition coastal migrations of ruling dynasties away from Kilwa.
This glossary entry is a part of the About.com guide to the Swahili Culture, and the Dictionary of Archaeology.
Wynne-Jones S, and Fleisher J. 2010. Archaeological Investigations at Songo Mnara, Tanzania, 2009. Nyame Akuma 73:2-9.
Wynne-Jones S, and Fleisher J. 2012. Coins in Context: Local Economy, Value and Practice on the East African Swahili Coast. Cambridge Archaeological Journal 22(1):19-36.