Place events into large historical periods.
the long era when stone tools dominated
the era of bronze tools, early states, and expanding trade
the era when iron tools spread and larger empires emerged
the era associated with ancient Greece and Rome
the period between ancient and early modern history in Europe and the Mediterranean
the era of revived classical learning and major artistic change
the era of long-distance oceanic exploration and growing global contact
the era when modern scientific methods took shape
the era emphasizing reason, rights, and criticism of old authority
the era of mechanization, factories, and rapid urban growth
the era of expanding colonial empires and global competition
the era of global war and the collapse of old empires
the years between the world wars marked by instability and ideological conflict
the era of global war, genocide, and massive geopolitical change
the era of superpower rivalry after World War II
the era shaped by satellites and human space exploration
the era shaped by computers, digital networks, and data
the human past before written records