1.) Prehistoric (300,000 B.C. - 10,000 B.C.) The dawn of Homo Sapiens in Africa to Göbekli Tepe and settlement of Jericho. All the early lithics before the Neolithic!
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2.) Neolithic (10,000 B.C. - 5,000 B.C.) The beginning of simple agriculture, through the Chalcolithic, to the start of the first empires of Sumer.
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3.) Ancient Antiquity (5,000 B.C. - 1,200 B.C.) Begins with the empires of Mesopotamia, through the unification of upper and lower Egypt, sees the Pyramids Built.
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4.) Classical Antiquity (1,200 B.C. - 323 B.C.) Starts after the Bronze Age collapse, ends after Alexander the Great dies and his legacy destroyed. Rome rises.
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5.) Axial Antiquity (323 B.C. - 235 A.D.) The good ol' days! Hannibal, Ceasar, Cleopatra, Augustus, Jesus, Caligula, Nero. Ends when the crisis of the third century begins.
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6.) Late Antiquity (235 A.D. - 476 A.D.) Rome never recovers and begins losing endlessly. Glorious generals keep getting backstabbed by barbs. Rome falls at end.
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7.) Early Medieval (476 A.D. - 1066 A.D.) Islam rises, Byzantium shines in the east, the Chinese invent gunpowder. Europe is in the dark ages getting sacked by Vikings!
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8.) High Medieval (1066 A.D. - 1337 A.D.) The battle of Hastings ends the Viking age. The crusades, Genghis Khan. Ends at the start of the Hundred Years War.
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9.) Late Medieval (1337 A.D. - 1453 A.D.) Black Death ravages the old world, Hundred Years War sees the rise of gunpowder on the battlefield. Constantinople falls at end, and with it the last remnant of Rome truly falls.
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10.) Post-Medieval (1453 A.D. - 1648 A.D.) Intellectuals fleeing Constantinople trigger the Italian Renaissance, the age of colonization begins. Wars of the Reformation ravage Europe. Millions of natives die from Spanish conquistadors. Millions are enslaved in Africa and brought to toil in the new world as well.
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11.) Neoclassical (1648 A.D. - 1799 A.D.) The end of the 30 Years War establishes the concept of sovereignty within Europe. From now on balance of power and the concept of world order is the main way in which Europeans respond to rivals. Long gone are the wars of religion as intellectualism and rationalism slowly erode the previous ideals. Constitutionalism, modern representation, and the rise of free market capitalism takes place. The enlightenment sweeps the west and with it a wave of rebellious activity takes place. The U.S.A. gains its independence. Ends at the end of the French Revolution.
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12.) Industrial (1799 A.D. - 1893 A.D.) New modes of production due to technological advances change human history forever. Factories, railroads, steamboats, ironclads.
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13.) Progressive (1893 A.D. - 1920 A.D.) Women gain the right to vote in New Zealand. Universal suffrage sweeps the world. Other progressive movements gain traction. Trust busting activity and union strikes dominate to reign in corporate greed. WW1 ends the last of the absolute monarchs of Europe. Communism achieves its first victory by gaining state power within Russia. Women in the U.S.A. gain the vote in 1920. Prohibition a product of the Women's suffrage movement also begins.
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14.) Modern (1920 A.D. -1945 A.D.) The interwar years up until the end of WW2. Afterwords the Bretton Woods agreement sets the global exchange of currency and pegs it to the U.S.A. dollar which in turn is backed by gold. The United Nations too is founded after its predecessor the League of Nations failed to prevent the war.
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15.) Atomic (1945 A.D. - 1969 A.D.) After the Atomic bombings of Japan. Nuclear research and development accelerate as does the cold war. Space exploration is spun off from this research and culminates in 1969 with the first lunar landing.
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16.) Post-Modern (1969 A.D. - 1991 A.D.) 1969 is the summer of love, a sign of rapidly changing social values. Second wave feminism brings women more prominently into the workforce. Neoliberalism rises and uses globalism to decouple companies from accountability toward unions by offshoring jobs overseas. Gold is decoupled from the dollar and the Bretton Woods system is abandoned to more easily facilitate overseas manufacturing.
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17.) Digital (1991 A.D. - 2007 A.D.) The Soviet Union breaks apart and with it the cold war. The rise of the internet and spread in the popularity of the personal computer revolutionizes society. Sid Meier's Civilization 1, 2, 3, and 4 are released!
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18.) Social (2007 A.D. - 2020 A.D.) Steve Jobs drops the first iPhone. With it the internet becomes even more accessible and accelerates the then rising social media platforms and big tech. The age of Memes begins. Sid Meier's Civilization 5, and 6 are released!
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19.) Biotech (2020 A.D. - 2077 A.D.) COVID-19 fueled the rise of mRNA vaccine and experimental drug treatments while also significantly disrupting the previous era's interconnectedness, even triggering global decoupling as nation states begin new rivalries and supply shortages create less of a pie for everyone else. Global Warming is further exacerbating the recovery of said supplies, perhaps creating a resource crisis if gone unchecked. Nevertheless, the increasing availability of CRISPR and increased venture capital and speculation (perhaps risen in part by the rise of cryptocurrency) into the biomedical industry will further develop genetic based capabilities. Whether for good or ill, genetic chimeras of all sorts are likely to be produced before the era is out.
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20.) Nanotech (2077 A.D. - 2100 A.D.) The Elon Musk Neuralink and Mark Zuckerberg Metaverse cerebral cortex integrated simulated interface dystopian cyberpunk future. Cyberpunk 2077, dawn of nanotechnology spurred on from experimentation of extreme biosciences from the previous era. Megacorporations run by big tech bros rule the world. Cryptocurrency and NFTs are the only currency. Traditional nation states become increasingly irrelevant as these corporations slowly creep in and pledge to solve all the problems that governments either could not solve, refused to solve, or simply failed for not resolving conflicts in the previous era.
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21.) Transhuman (2100 A.D. -

) Something happens along the way whereby due to technology humanity kinda ceases to exist. Slow conversion into cyborgs then robots, consciousness uploading, self-biogenetic modification into new species, a replacement by hostile AI, or aliens. Hence transhuman, as in going beyond human and or being replaced/exctincted.
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And no, I don't care if this is slightly Eurocentric. Civ has always been about gamifying history, that premise alone can never be pure. Fun and rule of cool should be sufficient, this is a theoretical civ 7 and if it is to be good it needs to be better than any civ game ever made before. It must be like the second coming of Christ, otherwise future iterations in the franchise simply won't be worth it. The brand will go stale.