Gukurahundi refers to the attempted genocide of the Ndebele by Robert Mugabe's 5th Brigade soon after Zimbabwe gained independence.
There has long been strong feelings between the majority Shona people of Zimbabwe and the Ndebele people in the south of the country. It stems back to the early 1800s when the Ndebele were pushed from their traditional lands in what is now South Africa by the Zulu and Boer. The Ndebele arrived in what is now known as Matabeleland, and in turn pushed out or required tribute from the Shona living in the region.
Independence came to Zimbabwe under the leadership of two distinct groups, the Zimbabwe African People's Union (ZAPU) and the Zimbabwe African National Union (ZANU). Both had emerged from the National Democratic Party in the early 60s. ZAPU was led by Joshua Nkomo, an Ndebelel nationalist. ZANU was led by the Reverend Ndabaningi Sithole, a Ndau, and Robert Mugabe, a Shona.
Mugabe quickly rose to prominence, and gained the post of prime minister on independence. Joshua Nkomo was given a ministerial post in Mugabe's cabinet, but was removed from office on 17 February 1982 -- he was accused of planning to overthrow Mugabe. At the time of independence North Korea offered to train Zimbabwe's army, and Mugabe agreed. 106 Military experts arrived and began work with the 5th Brigade. These troops were now deployed in Matebeleland ostensibly to crush pro-Nkomo ZANU forces, who were, of course, Ndebele.
Gukurahundi, which is Shona for 'early rain that washes away chaff', lasted for four years. It was mostly brought to an end when Mugabe and Nkomo reached a conciliation on 22 December 1987, and they signed a unity agreement. Although thousands were killed in Matebeleland and the south-east of Zimbabwe there was little international recognition of the extensive human rights abuses (called by some an attempted genocide). It was twenty years before a report was undertaken by the Catholic Commission for Justice and Peace and the Legal Resources Foundation of Harare. Estimates for the number of dead vary from 20,000 to 80,000.