Below is a list of all the sub-topics and sub-sub-topics contained under the History header in the Encyclopaedia Galactica.

-13.7Gy - 7000B.T: Preterragen Era

-7000 - -270AT: Pre-Spaceflight Old Earth
Agricultural Age
Atomic Age
Bronze Age
Industrial Age

030 - 900AT (2000-2900c.e.): Interplanetary Era
030 - 130AT (2000-2100c.e.): The Information Age
130 - 430AT (2100-2400c.e.): The Interplanetary Age
430 - 530AT (2400-2500c.e.): The Nanotech Age
530 - 900AT (2500-2900c.e.): The Nanoswarm Age

0900 - 3200AT: Interstellar Era
0900 - 1200AT: The Early Federation Age
1200 - 1500AT: Middle Federation/Megacorps
1500 - 2100AT: Late Federation/AI Emergence
2100 - 2600AT: The Age of Expansion
2600 - 3200AT: Age of Establishment

3200 - 5350AT: Inner Sphere Era
3200 - 3800AT: Age of Interstellar Empires
3800 - 4450AT: The Second Federation
4450 - 4650AT: The Version War Period
4650 - 5350AT: The ComEmp Period

5200 - 7700AT: Post-ComEmp Era
5200 - 5400AT: Age of Fragmentation
5400 - 5800AT: Age of Re-Evaluation
5800 - 6700AT: Age of Separate Empires
6700 - 7200AT: The Age of Crisis
7200 - 7700AT: The Central Alliance

7700 - 10,400AT: Outer Volumes Era
7700 - 9999AT: Age of Expansionist New Empires

9999AT - Present: Current Era