nomads and african farmers
The nomads and farmers weren't always bitter towards each other. The cattle-herding Arab nomads who lived in the south received large areas of land while the camel-herding Arab nomads who settle in the north never received any land due to the larger population. The farmers would welcome the camel-herding nomads when they came to feed their camels, and the nomads would deliver the farmers goods to the market. This relationship was soon broken when droughts came upon the land and destroyed the crops. The farmers who feared grazing a camel would destroy what's left of their land began to chase the nomads away. This force the nomads to search for other routes, and it had also created the tension between the two.