|Pre-Spaceflight||Up to 1950||Earliest era referred to, where humanity resides only on its planet of origin, Terra.|
|Early Spaceflight||1950 – 2005||Early solar system restricted spaceflight.|
|Star League||Age of War (First Exodus)||2005 – 2242||The time of the Western Alliance, early Terran Alliance, and earliest interstellar colonies. The Outer Reaches Rebellion resulted in the Demarcation Declaration, the forced independence for most colonies.|
|Star League||Age of War (Second Exodus)||2242 – 2398||Colonists on marginal worlds resettle or perish. The Terran Alliance collapses; the beginnings of the Terran Hegemony and the Great Houses of the Inner Sphere.|
|Star League||Age of War||2398 – 2570||The time of the Terran Hegemony and "civilized" warfare between the Inner Sphere houses. The first BattleMech is created.|
|Star League||Star League||2571 - 2780||The time when the Star League reached the height of its power and was destroyed by the Amaris Coup.|
|Succession Wars||Early SW||2781 – 2900||When the Great Houses vied for supremacy and many of the advances of the Star League disappeared as LosTech.|
|Succession Wars||Late SW||2901 – 3049||When the Great Houses vied for supremacy and many of the advances of the Star League disappeared as LosTech.|
|Clan Invasion||3050 – 3061||The time between the beginning of the Clan Invasion and the Inner Sphere's victory at the Great Refusal.|
|Civil War||3062 – 3067||The years in the shadow of the Federated Commonwealth Civil War.|
|Jihad||3068 – 3080||The time when the Word of Blake unleashed its Jihad.|
|Dark Age||Republic||3081 – 3130||The time from the defeat of the Blakists to the creation of The Republic of the Sphere.|
|Dark Age||Dark Age||3131 –||The time since the collapse of the HPG network caused political chaos in The Republic of the Sphere that lead to the militarization of Industrial Mechs and other civilian equipment.|
- Master Unit List: Battle Value, p. 2: "Era Legend"
- Catalyst Game Labs: "Classic BattleTech Eras"
- The Periphery, p. 12: "First Exodus"
- The Periphery, p. 14-19: "Beyond the Farthest Star" & "Inner Sphere Politics"
- Strategic Operations, p. 167: "Faction Quality Table"
- Catalyst Game Labs' forum: "Topic: The Republic era?"