122     Roman forces begin building Hadrian's Wall, a barrier intended to protect Roman citizens from Picts, or native Scots, on the isle of Britain. The wall is a sign that the Roman Empire has ceased to expand and will begin to shrink in coming years.

135     Banished from Jerusalem by the Romans, Jews begin to spread throughout the Mediterranean.

180     The death of Roman emperor Marcus Aurelius marks the end of the "Pax Romana," or Roman peace. Years of instability follow, and although Rome recovers numerous times, this is the beginning of Rome's three-century decline.

220     The Han dynasty of China comes to an end, plunging the country into three centuries of turmoil.

c. 300     Mayan culture enters the Classic Period, which lasts until 925, during which time the Maya undertake the vast majority of their most important building projects.