These are highlights about the history of the world. I'm posting them here because someone recently made a 5-word comment about some year in the third century that made no connection in my mind. I don't remember the details, but it was a quick and stylish factoid grazing that I really appreciated. This had me thinking: I'd like to know just one thing about each century. Here they are:

1st Century (0-100 CE)

The spread of Christianity following Jesus's death (c. 30-33 CE)
The consolidation of the Roman Empire under Augustus and successors

2nd Century (101-200)

Peak of the Roman Empire under the Five Good Emperors

Specifically, The Five Good Emperors, the ancient Roman imperial succession of Nerva (reigned 96–98 ce), Trajan (98–117), Hadrian (117–138), Antoninus Pius (138–161), and Marcus Aurelius (161–180)

The Silk Road trade reaches its height, connecting China to Rome

3rd Century (201-300)

Crisis of the Third Century weakens Roman Empire
Rise of the Sassanid Empire in Persia

4th Century (301-400)

Christianity becomes official religion of Roman Empire
Roman Empire splits into Eastern and Western halves

5th Century (401-500)

Fall of Western Roman Empire
Establishment of post-Roman kingdoms in Europe

6th Century (501-600)

Justinian's reign and codification of Roman law
Birth of Islam (Muhammad born c. 570)

7th Century (601-700)

Islamic expansion across Middle East and North Africa
Tang Dynasty establishes golden age in China

8th Century (701-800)

Battle of Tours halts Islamic expansion into Western Europe
Charlemagne creates first post-Roman empire in Western Europe

9th Century (801-900)

Viking expansions begin
Invention of gunpowder in China

10th Century (901-1000)

Formation of the Holy Roman Empire
Agricultural revolution in Medieval Europe begins

11th Century (1001-1100)

Norman Conquest of England
First Crusade launches

12th Century (1101-1200)

Universities emerge in Europe
Angkor Wat built, marking height of Khmer Empire

13th Century (1201-1300)

Mongol Empire becomes largest contiguous land empire
Marco Polo's travels connect East and West

14th Century (1301-1400)

Black Death kills one-third of Europe
Rise of the Ottoman Empire

15th Century (1401-1500)

European Age of Discovery begins
Fall of Constantinople ends Byzantine Empire

16th Century (1501-1600)

Protestant Reformation splits Western Christianity
Spanish Empire becomes first global empire

17th Century (1601-1700)

Scientific Revolution transforms understanding of world
Rise of global trade companies (Dutch and British East India Companies)

18th Century (1701-1800)

Industrial Revolution begins in Britain
American and French Revolutions launch age of democratic revolutions

19th Century (1801-1900)

Spread of railways and telegraph creates first global communications
Rise of nation-states and modern nationalism

20th Century (1901-2000)

World Wars reshape global power structure
Digital revolution begins with the invention of computers