This timeline focuses on home world and core, other surviving star systems had different histories.
Approximately 11 000 BE: Humans invented writing on home world.
Approximately 5 500 BE: The time of the first great empires, with three great empires rising up on home world.
Approximately 3 500 BE: The first manned spaceflight on home world.
Approximately 3 350 BE: First human interstellar flight.
Approximately 3 200 BE: The colony war, where the human home world was bombed to stone age by AI controlled warships.
Approximately 2 800 BE: The forming of the Great Federation. It was apparently located spinward from the current area of the Empire.
Approximately 2 300 BE: The Great Federation has over 100 000 member worlds.
Approximately 1 800 BE: The Great Federation has over 500 000 member worlds.
Approximately 1 700 BE to 1600 BE: The Great Federation was destroyed in an attack from outside.
Approximately 1 700 BE: The colony on Core was founded and then cut off from the Federation early on.
Approximately 1 500 BE: The great civil war on Core.
Approximately 1 300 BE: The forming of the star kingdom on Core.
Approximately 1 200 BE: The star kingdom has colonies in about 100 other star systems.
Approximately 1 100 BE: The star kingdom is destroyed by a internal anti technology movement that was apparently motivated by the fear that the destroyers of the Great federation would find them if they spread out too much.
Approximately 1 000 BE: Civilization is practically nonexistent on Core, with only small scattered groups of survivors and no technology.
684 BE: The forming of the noble line that would eventually form the empire, as humans stated to rebuild civilizations again on Core.
559 BE: The First Conclave of Great Houses wrote the original charter regulating their relations. Technology is back to gunpowder weapons. (TL 4)
399 to 391 BE: The great war of houses: a great war between several of the houses causes a backslash forming of a common army to keep peace. The war was characterized by mechanized armies and airplanes. (TL7)
204 BE: Interstellar flight is again achieved on core(TL 9)
Approximately 200 BE to 100 BE: a lot of colonies are founded.
105 BE: The Second Conclave of great houses forms the common space fleet and space patrol and regulates the numbers of the great houses and the lesser houses.
94 BE: Signs that the Great Federation was indeed attacked by some alien race are found. This prompts an increase in the military preparedness and spending.
90 BE to 10 IT: This time saw the great building of “The first fleet”. Some ships from that fleet are still in use in large numbers. (Things like anson patrol ships, assegai and meteor fighters and Valyrie dropships)
55-54 BE: The short Human-Turian was was fought with first fleet ships. (TL 9)
0 BE Third conclave of Great Houses founded the Empire with the official name “The Imperium of Man” with Emperor Gustav as the head. The roles of the different branches of government are laid out.
Approximately 10 IT starts the building of “The great fleet”(TL 10) that forms the backbone of imperial fleet today, with designs like Admiral-class cruisers being built.
85-89 IT: several imperial task forces exchange fire with ships thought to be scout ships of the aliens that destroyed the great federation.
93 IT: was the start of “Great fleet rebuilding”(TL 11) prompted by new hostile aliens, the with the new designs taking over from the older in all military starship construction.
99 IT: now.