What was the mfecane how did it affect southern africa?

Mfecane, ( Zulu: “The Crushing”) , Sotho Difaqane, series of Zulu and other Nguni wars and forced migrations of the second and third decades of the 19th century that changed the demographic, social, and political configuration of southern and central Africa and parts of eastern Africa. The Mfecane was set in motion by the rise of the Zulu military kingdom under Shaka (c. 1787–1828), who revolutionized Nguni warfare. The rise of Shaka’s kingdom, which took place during a time of drought and social unrest, was itself part of a wider process of state formation in southeastern Africa, which probably resulted from intensified competition over trade at Delagoa Bay. The pattern of the Mfecane, in which tribe was set against tribe over an ever-increasing radius, was highly successful in areas weakened by overpopulation and overgrazing.

In South Africa itself the Mfecane caused immense suffering and devastated large areas as refugees scrambled to safety in mountain fastnesses or were killed, thus easing the way for white expansion into Natal and the Highveld. In the Cape Colony it greatly increased pressures on the eastern frontier as refugees known as Mfengu crowded in on the peoples of the Transkei. At the same time, however, as a result of the Mfecane, some of the most formidable kingdoms to oppose white penetration were created—the Sotho, Swazi, and Ndebele, as well as the Gaza of Mozambique.

The impact of the Mfecane was felt far beyond South Africa, as peoples fled from Shaka’s armies as far as Tanzania and Malawi in the northeast (the Ngoni) and Barotseland, in Zambia, to the northwest (the Kololo).

The Mfecane was partly caused by changes in the Nguni groups that resulted in the development of the Zulu nation. These changes led to Shaka Zulu's rise to power and his dream of a Zulu kingdom, and his military drive through southern Africa.

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uhh idk for sure but i think it makes it difficult to pump the oil through the oil rigs