The best known are in chronological order:
1. Herero War, German Southwest Africa, (1904-07): 75 000, Imperial Germany war against natives.
2. The Armenian Genocide by the Ottoman Empire (1915-1917). This genocide is vehemently denied by the Turkish government
3. The Nazi genocide of the Jews (1941), often referred to as the Holocaust
4. The massacre of the Tutsis by Hutus in Rwanda in 1994.
5. Various leaders such as Stalin, Mao, Idi Amin, North Korea, Romania, and other states have also done this.
The Genocide by Otoman Turkey in Armenia, The Nazi holocast in Germany, The Bangladesh (East Pakistan) killing by Pakistan
In two words the 20th century
Two famous people from the 20th century who helped shape this time are Muhammad Ali and Louis Armstrong. Also, Elvis and Ernest Hemingway are two other 20th century famous people.
1910 is 20th century Century=1st two digits of year +1
In two words the 20th century
Two examples that come to mind immediately were Saint Padre Pio of Pietrelcina in the 20th century and D. D. Home in 19th century England.
The Steelers won four Super Bowls in the 20th century. They have also won two Super Bowls in the 21st century.
There have been many revolutions during the 20th Century. Two include the Russian Revolution of 1917 and the Iranian Revolution of 1979.
January 1 1900
At the turn of the 20th century the term jazz had two spellings. The musical term Jazz was interchangeably used with jaz.
Vladimir Lenin and Joseph Stalin were two communist leaders of the USSR in the 20th century. Lenin ruled from 1917 to 1924. Stalin ruled from 1924 to 1953.
World war one: 1914-1918 World war two: 1939-1945
Two women soldiers of the 20th century are Lotus Mort (1940s) and Faye Glenn Abdellah (1970s). In the 19th century there was Dr. Mary Walker (1860s) and Lizzie Compton (Civil War).