The 20th century was the bloodiest period in human history, with world wars, genocide, concentration camps, the development of chemical and nuclear weapons, bombings, guerilla wars, and terrorist activities unheard before. As a result of this savagery, the number of dead is estimated in the hundreds of millions.
Joseph Stalin: Murderer of 40 million people
Why was the last century so bloody? First, advancing technology led to the development of weapons much more lethal than earlier ones. But the second and most important reason was that ideologies caused these weapons to be employed with terrible cruelty. The 20th century saw the violent harvest of the various "isms" that were founded in the 19th.
Communism, the bloodiest of these "isms," is by far the cruelest and also the most widespread. The number murdered by Communist regimes or organizations in the past hundred years stands at roughly 120 million. Just for the sake of this ideology, these people were removed from their homes, worked to death in concentration camps, exiled to perish on the Siberian steppes, subjected to the horrible tortures in the most horrible prisons, executed by brainwashed Communist militants, strangled, had their throats cut, or starved to death in deliberately-created famines.
The savagery of this red terror began first in Russia during the Bolshevik Revolution of 1917. It spread throughout the newly formed Soviet Union and from there, to eastern Europe, China, Korea, Vietnam, Cambodia, some Latin American countries, Cuba and Africa.