N-1,000,000 Founder (Forerunner, Anchients) Period.

N Rise of the First Galactic Empire, which spanned approximately a 500 LY area. This area of space will eventually become the domain of the Federated Suns. 

N+500 The Second Galactic Empire comes into being having conquered the First from the frontiers. The 2nd GE spans many hundreds of worlds. There is a time of great expansion as new technologies come into being.

N+950 The 2nd GE expands beyond the ability of the government to control it spanning almost 2/3rds of the Milky Way Galaxy and includes thousands of different Races.

N+1,700 Fall of the 2nd GE.
Dark Age.

N+3,000 Rise of the Third Galactic Empire.

N+5,300 Rise of the Fourth Galactic Empire.

N+7,400 The 4th GE spans a quarter of the Milky Way Galaxy. The leadership of the Empire has been, for the most part, a benevolent one.

N+8,000 The Galactic Mileau appear from the ashes of the 4th Galactic Empire. Being a coalition of various psionically empowered races that are attempting to pull all the other cultures of the Galaxy together and help in their development. 

DS 0 Rise of the Dominium Starleague
N+8,200 The planet Arakis is discovered within the boarders of the Starleague. The Navigators Guild discovers the power of the spice Milange.

DS400 Rise of the Power, originally an insignificant group of core worlds Rimward and Trailing the Starleague.

DS1,900 Rise of the Romulan Empire whos home worlds are Coreward and Trailing that of the Power.

DS2,340 First contact between the Power and the Dominium Starleague, war ensues over the mining of a system rich in the minerals necessary for production of FTL Drive cores.

DS2,348 First appearance of representatives of the Galactic Mileau, they step in and offer to negotiate a peace treaty between the opposing starcultures.
Then next few hundred years sees the three major Starcultures in this arm of the Milky Way Galaxy conducting intense exploration and colonization and expansion of the areas out from their homeworlds.

DS3,600 The Dominium Starleague expands too fast for its own good, political infighting, a coup attempt against the Emporer (which starts a minor civil war) and an armed conflict with the Romulan Empire shatters the Starleague.

DS3,740 The DS consolidates its position in the MW Galaxy and retreats its boarders away from the Romulan empire. The void that is created is left with hundreds of populated worlds that suddenly find themselves with out a ruling body or government. Numerous self styled Emperors/Warlords/Criminal organizations/Confederations and comunes sprout up and die over the next millenium. The Waring States Period.

DS4,190 The Galactic Mileau begins to disperse its StarGates for use by the Starleague, Romulan Empire and the Power to aid them in the expansions of their local space. The StarGates are spaced approximately 6-800 LY apart.
This allows for the exploration of their respective areas of space to increase geometrically. The GM, however, will not transport large military fleets, nor aid in wars between the starcultures.

DS4,300 The First Lensman appears on the scene and begins to bring law and order to the Galaxy.

DS4,820 Finding themselves pretty much surrounded on all sides by hostile starcultures, the worlds that were left in the Void of the DS retreat, come together for the first Galactic Senate Conference to discuss the formulation of what will come to be known as the Federated Suns. The Galactic Mileau is present to aid in the negotiations.

FS 1, DS4,850 The Federated Suns is Born.

FS460, DS5,310 After seeing the power that a joined society can offer from the success of the FS, a number of independent planets Spinward of the Federated Suns join together to create the Oolong Combine.

FS875, DS5,725 The First Bug War, the Starleague falls under the attack of a swarm of bugs, so sudden and widespread was the initial assault that they found themselves in very dire straits. Both the Power and the Federated Suns seeing the Bugs as a threat to themselves should the DS fall, step in and lend aid to the DS forces. During the war the Bugs are successful at launching multiple attacks into the interior or both the Power and the FS.

FS930, DS5,780 The rise of a Galactic criminal organization known as Boskone. Originally a small group of worlds controlled by a Pirate Warlord on the fringes of the FS (a leftover of the Waring States Period that remained out of the mainstream of FS society), they move in and take advantage of the confusion of war to generate blackmarkets, arms smuggling, and drug running across this arm of the MWGalaxy.
They become the main opponents of the Lensmen and the Galactic Patrol of the GM.

FS1,700, DS6,550 The Galactic Mileau begins to bring the 5 major starcultures in the area together to attempt to create a Confederation, the Dominium Starleague, the Federated Suns, the Power, the Romulan Empire and the Oolong Combine. More than anything else they are attempting to bring about peace in the Galaxy and to stop the battles and skirmishes that break out between the various governments

FS3,000, DS7,850 The current social order. The Romulan Empire is the last to join the Confederation. this is a time of celebration.
This doesn't mean that there is absolute peace…… but at least there is an attempt to resolve political issues by negotiations before the guns come out. Travel between the various starcultures is fairly common. The Federated Suns and the Oolong combine have an open boarder between them (like between the USA and Canada).
There is some significant tension between the Starleague and the Power, and between the Federated Suns and the Romulan Empire.
The Power and the Romulan Empire have a fairly solid relationship tho they do not have an open boarder between them.
The Federated Suns the the Starleague have a good neutral relationship, they share quite a bit of technology and resources.
The Starleague and the Oolong Combine do not get along at all….. there is a section of space in the Combine that the current Emporer of the DS is attempting to annex, tho nobody is quite sure why, and this causes constant strain on their relationship.