A Cache of Hippopotamus Ivory at Gao, Mali; and a Hypothesis of Its Use
Insoll, Timothy, Antiquity
The cache of hippopotamus ivory at Gao
The city of Gao is located on the Niger Bend within the Sixth Region of the Republic of Mall, approximately 1100 km from the capital, Bamako [ILLUSTRATION FOR FIGURE 1 OMITTED]. Although Gao developed as a terminus for trans-Saharan trade prior to 1000 AD, it is famous historically as the capital of the Songhai empire which was at its height between the mid 15th and late 16th centuries AD. The last of the three great medieval West African empires, the Songhai empire was preceded by the empire of Ghana which flourished from the 9th to the 11th centuries AD, and by the empire of Mali which reached its peak in the early 14th century AD (Insoll 1993a: 629).
A cache of hippopotamus tusks was uncovered during excavations conducted by the author in conjunction with the Malian Institut des Sciences Humaines in Gao in September and October 1993. The number counted to date is 53 but the final number will not be known until conservation is complete, funds for which are urgently being sought. The tusks were found towards the base of a multi-period site in old Gao (Gao Ancien) with five occupation layers (Periods 1-5), and were associated with period 4 which has been provisionally dated to the 10th-11th centuries AD. An assemblage of pottery and glass of North African and Spanish origin, found above and sealing the tusks in a period 3 deposit, has been dated by Rachel Ward of the Department of Oriental Antiquities, the British Museum, to the 11th and 12th centuries AD, with a couple of sherds of possible 10th-century date.
The tusks had been placed within a pit, cut to a maximum depth of 160 cm below the surface level into the period 5 deposits [ILLUSTRATION FOR FIGURES 2 & 3 OMITTED]. Two slivers of wood survived underneath the tusks, one 8 cm long and the other 6 cm long, with a dark brown organically rich linear deposit in very localized contexts, suggesting the tusks were placed upon wooden beams. A pottery jar, or bottle neck, and a knife blade haphazardly placed in association with the tusks do not appear to be significant.
It is possible that this cache represents a ritual deposit. Recent fieldwork in the Republic of the Sudan has found hippopotamus tusks in ritual contexts, with tusks placed on top of burial tumuli dated to between the 2nd and 4th centuries AD (Edwards pers. comm.). However, no evidence of such kind was found during the excavations at Gao dating from this period - no burial, no other indications of ritual, and, at present, there is neither archaeological nor historical evidence from this region to indicate that the burial of hippopotamus tusks formed part of a wider ritual system. Yet a variety of evidence indicative of participation in trans-Saharan trade was found above the layer containing the cache, and the additional fact that only the incisors and canines, the teeth of use to an ivory worker, were present (Krzyszkowska pers. comm.) suggests that an alternative hypothesis to a ritual explanation for the presence of this cache can be proposed; that the tusks represent a shipment of ivory, carefully buried, and later not retrieved.
The hippopotamus and the elephant
The hippopotamus (Hippopotamus amphibius) was originally found throughout Africa south of the Sahara, in areas with deep waterways. Small populations are still found in the river Niger, and the hippopotamus was present in the Nile Delta until the 17th century AD (Krzyszkowska 1990: 20; Nowak 1991: 1348-50).
The preferred habitat of the hippopotamus is an area of deep, permanent water with adjacent reedbeds and grassland, which suits its diet of grass. The population can be very dense, as high as 7 per 100 m of lake shore and 33 per 100 m of river length (Nowak 1991: 1348-9). At the period when the tusks were cached, conditions in the River Niger, both up and down river from Gao, would have been ideal for the hippopotamus, as humid conditions were pronounced c. …