The tech tree will probably have to be divided into different eras. I spent some thought on the matter and came up with the following approximation. It might be too Europe-centred though. I don't know much about East Asian history (Ming and Qing and stuff).
Most of the stuff here is quite obvious but I may edit when I think of anything to add.
Dates and events are indicative only.
Age of Discovery
Dates: ~1450-1600
Events: European explorers set out, discovery of America, Inca and Aztec conquests, beginning of colonization, European Renaissance, spreading of the Printing Press, the Reformation, fall of Constantinople and rise of the Ottomans, etc.
Techs (units/buildings/civics): optics, gunpowder, printing press, caravel, compass, maps, astronomy, mercantilism, Renaissance art
Colonial Age
Dates: ~1600-1750/1800
Events: European expansion around the world, intensive colonization of the Americas, first struggles for independance (USA), the Enlightenment, the Glorious Revolution, the end of the Ming dynasty, unification of Japan
Techs: more advanced gun stuff, colonies, galleons and other big wooden ships, nationalism, liberalism, constitution and democracy, secular state, early physics (Newton), calculus, baroque, classical music
Industrial Age
Dates: ~1750/1800-1900
Events: industrial revolution, rise of capitalism, big European overseas empires, independance of many colonial states, scramble for Africa, development of modern science, Napoleonic wars, unification of Italy and Germany
Techs: steam power, steamships (make them better!), railroads, oil, automobile, engineering, physics, chemistry, biology, electricity, radio, Eiffel Tower, medicine, steel, romantism
Machine Age
(This one is there to separate the Industrial Age and the late 20th century. According to Wikipedia the 1900-1950 period is called Machine Age. I'm not sure if it fits though.)
Dates: 1900-1950
Events: the apex of the colonial empires, colonial tensions between the Europeans, WWI and II, the Great Depression, rise and fall of fascism, birth of the USSR, end of the colonial empires, Chinese civil war, independance of India and other colonies, atomic bomb, League of Nations, United Nations
Techs: communism, fascism, tanks, modern guns, aviation, unions, taylorism, interventionism, fission, quantum physics, television, art deco, cinema, rockets
Information Age
(Other candidates for the second half of the 20th century were the Atomic and the Space Age, but I left them out because they're too specific. "Information Age" wasn't really used before the 1980, but computers are older than that.)
Dates: 1950-
Events: decolonization (last colonies become fully independant), oil crises, rise of environmentalism, globalization, establishment of the People's Republic of China, fall of the USSR, cold war, development of computers and Internet, rise of Islamic fanatism
Techs: mass media, computers, networks, Internet, satellites, space exploration, neo-liberalism, fair trade, ecology, rock music