Summary Timeline
5,000 ya ........................................... First cities and states in N.W. Africa and
S. Mesopotamia.4,000 ya ........................................... First multicity empires; cities and states
in India and China.2,500 ya ........................................... First superempire (Achaemenid Persia);
¿ rst states in Americas?2,000 ya ........................................... Roman, Parthian, Kushan, and Han
Empires À ourish.800 ya .............................................. Mongol Empire, largest land empire
ever created.650 ya .............................................. Black Death.500 ya .............................................. Different world zones linked by sea:
Columbian exchange.300 ya .............................................. Scienti¿ c Revolution.200 ya .............................................. First industrial revolutions; ¿ rst
“democratic” revolutions.100–50 ya ........................................ Western imperialism; First World War;
anticolonial revolutions.50 ya ................................................ First nuclear weapons.0 ya .................................................. Rising consumption levels; serious
damage to biosphere.50 years from now (yfn) ................. Global populations stabilize?4 billion yfn ..................................... Sun expands, destroying planets,
before dying.