Good that fits well 

Basically, the Collective got stuck in an endless war, inter universal stuff, specifically in their slipspace, which js vitally important to them. This resulted in the Secondary Universal Cataclysm Disaster when the Triarii attempted to use a new piece of technology. This resulted in insanely dangerous storms in the Secondary Universe, thus rendering transport through the slip space to the other galaxies implausible. The Collective was unable to remove these Storms, which are estimated to end in approximately half a million years time. This also resulted in a new solar phenomenon known as 'Tears'. These tears are relatively rare but extremely dangerous when they appear, a literally hole in the fabric of space time as the barriers between the Primary and Secondary universe collapse and sections of the secondary universe leak through. In the Milky Way (and likely several other parts of the universe) these tears are relatively harmless due to the lack of anything that will leak through. Thus all that happens in these tears are the laws of physics being replaced by the other universes laws. These tears are also minor on size, most barely the size of Jupiter. These tears, having little energy flowing through them, usually close themselves after a shirt time
In many other parts of the universe however, it is a different story. The tears crack open and the storms leqk through from the other universe, forcing the crack wider as they do. These are larger, some being many light years in size. It is estimated that these will only close once the associated storms have cleared up. There is no accurate way of telling how much damage has been done in the other galaxies as a result of these tears.
With a collapse of their intergalactic capabilities, the Collective could not defend its extra galactic holdings, and as the tears leaked Storms through it became implausible even to brave the long trek across the gaps between galaxies, lest entire fleets be consumed. These tears weakened not just the barrier between the primary and secondary universes, but other universes as well, and this allowed for the arrival of more extra universal entities, and the Collective was locked in a losing battle for many, many years. Tens of millennia passed before the threat finally passed, and what was left of the Collective, drastically reduced in size, man power etcetera, stood upon an island of corpses in a sea of blood. Although crushed, they had held. The audio file of the Greater Good prevails played through the streets for the first time in living memory... But there was no celebration, no joy. Everywhere one looked they would see death, they would see decay. Many had known only war, and it was branded the single most horrific war in Collective History.
For the cycle following, an Umbrae Populus song, dium'zul, dominated much of the requested audio files.
Excerpt: "Dweade a doi e'tol, no'l Card'aid bachk er soli'on rro nod ywr, mi dium ond zai, hurl'wym er pam gollais aid... "
Translated "Tell me you shall not come back, love since you have fell away, I have only the darkest of shadows now, no summer for my souls desire..." 
Followed closely by perhaps the oddest trend in Collective history, a Saeva Simius song.