Oil and Water in Sudan 209
The Dinka occupied fringes of the basin offering larger dry areas during
the rainy season, and correspondingly greater opportunities to utilise agri-
culture as an element of their economy. The environmental basis of Nuer
economic prosperity hinged on control of the best grazing lands, found in the
wettest parts of the basin. The Nuer adapted to the "dead flat clay plain" sub-
ject to extreme flooding in the rainy season. This area of poorly drained clay
soils is only marginally suitable for cultivation and prone to crop failure, but
provides the richest pasture for their cattle. At least part of the value of the
area was in the diversity of forage gra~ses?~
Their relatively low agricultural productivity forced the Nuer to maximise
their herd sizes by whatever means possible, including raiding, in order to
substitute milk and meat for plant foods. A greater area susceptible to flood-
ing acted to reinforce the Nuer cattle monoculture, while also presenting an
opportunity to increase the size of their herds. Because cattle reproduce at a
greater rate than humans, inflated bride wealth levels were a natural outcome
of the expansion. But as the data cited above indicates, the number of cattle
required could also shrink with shifts in the demographic and environmen-
tal parameters.
Bride wealth appears to be a dependent variable that varies with the
respective modes of production. The amount of bride wealth paid is a con-
sequence of the need for and availability of labour: mobility increases this
need. Because the Nuer are more mobile than the Dinka, more labour is
required to manage the cattle. The Nuer3 inflated bride wealth was, there-
fore, also a function of rising labour requirements created by territorial
expansion.
A mode of production that secures for its populalion a greater number of
cattle is clearly advantageous in the Nuer environment. This advantage is
more acute in times of critical food shortages due to the frequent incidence
of floods and occasional drought experienced on the clay flood plain. Nuer
grain supplies are particularly susceptible to such disasters (83% are floods):
resulting shortages are reported to occur with a four-in-ten probability for
several central and Zeraf Nuer groups." The Ghazel-Jebel triangle, occupied
by the Nuer Jikany, Jagei, Leik, and Dok, is the "most extreme ecological"
environment in the region, and is subject to "almost total flooding in the wet
season".28 Livestock provided a means to procure other food supplies in the
face of what were often severe grain shortages.
Even in circumstances where the Nuer strove to maximise the production
of animal resources, grazing area alone could not have been the sole focus of
Nuer-Dinka competition. Also in short supply in the central basin was dry
land upon which a human population could live at the height of the rainy
season and shelter their cattle.z9 This explains why the territorial conflict
went beyond the marginal lowlands previously utilised by the Dinka on an
occasional basis.