You can't really say when genocide did occur as it still happens today. But if you are trying to find out about some events here are some:
World War II 1938-1945, the Holocaust occurs - over six million Jews are slaughtered by the Nazi Regime
Somali Civil Wars 1991 - Present, 350,000 - 500,000 dead (many due to starvation). Any of you guys seen "Black Hawk Down"?
Srebrenica Massacre, July 1995, 8,100 Bosniaks killed by Serb Army of Republika Srpska (VRS). Seen "Behind Enemy Lines"? That movie is based on this event.
So yeah, if you search these up you will find out why as well.
Genocides have happened through out history, so your question is too broad and can't be answered. Give dates and places so it can be answered.
M
everywhere
The summer olympics, like the winter olympics occure, every four years.
Genocide Genocide
in the ocean :P
plasma membrane
rajsthan
August 29 2005.
leaves
Stage 4.
Europe and Asia.
chemical weathering living organsims