That is still quite an overwhelming challenge. Off the top of my head I could break it down into:
-political reforms (French revolution, Napoleon civil code, French republic and its presidents. American constitution. Russian Bolshevik revolution, the rise of communism, with the Russian one vs. the Chinese one having different flavours. Decline of colonial powers and emergence of brand new states. Abolition of slavery. Women’s rights. Bourgeoisie and working class and declining nobility. Federalization. Etc.)
-scientific and technological advances (Ink pencils. Steam powered mechanisms. Electricity. Oil based automotive industry. Airplanes. Space rockets, satellites. Vaccines, antibiotics, aspirine, antipsychotics lol. Theory of relativity, quantum physics. Radio and television. Cybernetics, computers, telephones, printers. Refrigerators, microwave ovens, washing machines. New materials: plastic, kevlar, nylon. Atomic weapons. Etc.)
-artistic movements (late classicism, romanticism, naturalism, impressionism, cubism, expressionism, art deco, jazz, blues, rock&roll, heavy metal, hip hop, reggae, Sci-Fi literature etc)
-wars (civil wars in Italy, USA, etc. Continental wars in North America, Europe, Asia, Middle East. Two worldwide conflagrations. The Cold War. The silent cyber war between hacker factions.).
-globalization (English as international lingua franca for business and not only. European Union, United Nations, UNESCO, UNICEF, Red Cross, Red Crescent, Interpol, NATO. Nobel prizes. Immigration policies, Green visa, multiple citizenship. Etc.)
-diplomacy
-secret services
-new health concerns (HIV, Ebola, Bird flu)
-new demographic and ecological concerns (greenhouse effect, overcrowding, wild life extinction, deforestation, marine life perturbations, desertification).
So, which one tickles your fancy ?