Chronology of civil war in Darfur
August 7, 1983: Zaghawa and Mahariya against the Fur
The drought of the early 1980s drove nomadic Zaghawa and Arab groups southwards into the central Fur region of Jebel Marra.
Some sought water and pasture for their animals, but many lost so much animal wealth that they were seeking to settle permanently.
The Zaghawa who moved to urban centres had some success in petty trade, but those who kept to rural areas encountered hostility from the Fur farmers who realized that the move might this time be permanent and from government forces who accused them of camel rustling.
The Fur elite in local government resisted the nomads' intrusion rather than seek accommodation.
Police and army burned down numerous Zaghawa settlements and extra-judicially executed local Zaghawa leaders.
The influx of modern weaponry increased dramatically: an estimated 50,000 AK47s, G3 rifles, RPGs and heavy machine guns were available in Darfur, equivalent to one for every adult male.
1987 to present: The Arab alliance against the Fur
The element of racial prejudice became further entwined with the environmental roots of the conflict with the formation of an alliance of 27 Arab nomad tribes and their declaration of war against the "Zurug" (black) and non-Arab groups of Darfur.
The response of the Fur was to form their own militias, at first for local self-defence and later as part of a short-lived but significant linkage with the SPLA.
The main aim of the nomads was to seize land, and they would often give notice to Fur villagers before the raids to make way for the "liberating" or "cleansing" forces.
Nonetheless, the toll on population and resources was high.
By the time of the 1989 peace conference, an estimated 5,000 Fur and 400 Arabs had been killed; tens of thousands had been displaced and 40,000 homes destroyed.
The Sahel drought, coupled with interference by government and the struggle for local political power, appears to have polarized the ethnic groups whose identities and inter-relationship had hitherto been fluid.
The only way out of the crisis will be the recognition of its environmental and developmental origins, and the negotiation of equitable access to resources in a fragile eco-zone.