Wiki has this to say about the dark years of Idi Amin's rule in Uganda during the 1970s.
Amin retaliated against the attempted invasion by Ugandan exiles in 1972 by purging the army of Obote supporters, predominantly those from the Acholi and Lango ethnic groups. In July 1971, Lango and Acholi soldiers were massacred in the Jinja and Mbarara Barracks, and by early 1972, some 5,000 Acholi and Lango soldiers, and at least twice as many civilians, had disappeared. The victims soon came to include members of other ethnic groups, religious leaders, journalists, senior bureaucrats, judges, lawyers, students and intellectuals, criminal suspects, and foreign nationals. In some cases entire villages were wiped out. In this atmosphere of violence, many other people were killed for criminal motives or simply at will. Bodies floated on the River Nile in quantities sufficient to clog the Owen Falls Hydro-Electric Dam in Jinja on at least one occasion.
The killings, motivated by ethnic, political and financial factors, continued throughout Amin's eight-year reign. The exact number of people killed is unknown. The International Commission of Jurists estimated the death toll at no less than 80,000 and more likely around 300,000. An estimate compiled by exile organizations with the help of Amnesty International puts the number killed at 500,000. In August 1972, Idi Amin declared what he called an "economic war", a set of policies that included the expropriation of properties owned by Asians and Europeans. Uganda's 80,000 Asians were mostly from the Indian subcontinent and born in the country, whose ancestors had come to Uganda when the country was still a British colony.
Many owned businesses, including large-scale enterprises, that formed the backbone of the Ugandan economy. On 4 August 1972, Amin issued a decree ordering the expulsion of the 60,000 Asians who were not Ugandan citizens (most of them held British passports). This was later amended to include all 80,000 Asians, with the exception of professionals, such as doctors, lawyers and teachers. A plurality of the Asians with British passports, around 30,000, emigrated to Britain. Others went to Australia, Canada, India, Pakistan, Sweden, and the U.S. Amin expropriated businesses and properties belonging to the Asians and handed them over to his supporters. The businesses were mismanaged, and industries collapsed from lack of maintenance. This proved disastrous for the already declining economy.