This has been done many times in the history of humankind, but I reckon you are thinking of the mass slaughter of Jews, Poles, negroes, gypsies and other peoples by Adolf Hitler and the Nazis during the Second World War. This is known as The Holocaust- the Nazis themselves called it 'The Final Solution'.
There are many tribal groups in Africa. You can't even count them, because there are yet to be discovered tribes in Africa and Nigeria alone has over 400 tribes and about 521 languages. so, I don't think there will be an exact number of the tribes in Africa.
Ethnic groups of what/where - specify so we can give you an answer.
The largest ethnic minority groups in the United States are African American,and Hispanic Americans
Kikuyu is the largest ethnic group in Kenya.
Colonizers ignored ethnic groups when drawing political borders. Most countries have diverse ethnic groups.
Massacre Ethnic cleansing Atrocity Pogrom
It was when the German Nazi Party killed millions of Jews. The Nazis leader "Adolf Hitler" called it ethnic cleansing.
800,000 were massacred during ethnic conflicts.
Urban ethnic concentrations are generally called neighborhoods, whereas rural concentrations are called ethnic islands and ethnic provinces depending on size.
The term "ethnic cleaning" or "ethnic cleansing" was not applied until the wars following the breakup of Yugoslavia in the late 20th century. So the Nazi genocide was not called ethnic cleansing, although today you could use that term to describe it. At the time, the Nazis called it "solving the Jewish problem" and other euphemisms. When initially widely recognized by the populations of the allies, it was called murder.
Inter-ethnic strife.
Vietnamese is its own ethnic group. Within Vietnam, the dominant ethnic group (which is externally called Vietnamese) is called Kinh (pronounced Kiñ).
Inter-ethnic strife.
Aborigine
There are way more than just 9 ethnic groups in the World.
Really? On earth?,,,,,,,,,,,,,,,,, War.
an ethnic group