Kassala is the capital of the state of Kassala in eastern Sudan. In 2002 its population was recorded to be 957,000. Built on the banks of the Gash River, it is a market town and is famous for its fruit gardens. Many of its inhabitants are from the Hadendawa people.

The Mahdist War was a war between the Mahdist Sudanese, led by Muhammad Ahmad bin Abdullah, who had proclaimed himself the "Mahdi" of Islam, and the forces of the Khedivate of Egypt, initially, and later the forces of Britain. Eighteen years of war resulted in the creation of Anglo-Egyptian Sudan (1899–1956), a de jure condominium of the British Empire and the Kingdom of Egypt in which Britain had de facto control over Sudan. The Sudanese launched several unsuccessful invasions of their neighbours, expanding the scale of the conflict to include not only Britain and Egypt but also the Italian Empire, the Congo Free State and the Ethiopian Empire.