The Hive used to only live very short lives, 10 years to be exact. They lived on a planet that had over 500 different races and 52+1 different moons. One of which was actually the Traveler. The Hive's king has a "dead larvae" that talked to him. It told him that the 52+1 moons would align, cause a great wave and destroy all life on the planet. The king had 3 kids as well.

During a war between one of their other races on the planet the king dies, one of his kids takes the dead talking larvae and ran away with the other 2 kids. The larvae told of a ship that could go to the planet's core. The kids find the ship, go to the core and find the Worms. The Worms are giganta-huge, trapped there by the Traveler, supposedly, and the moon alignments and the subsequent big wave was meant to kill the Worms as well as all life on their planet.

The Worms trick the kids into ingesting the larvae parasites so they can live longer, as well as tricking them into infecting all life they could on the planet and moons and destroy those that wouldn't comply. They did and in doing so made the Traveler flee, and ultimately allowed the Worms live.

The Worms told the 3 kids that if they wanted to keep living, they had to kill others or be killed. The Worms believe this to be the way of life and the universe, kill or be killed. This was as a means to feed the kid's, as well as other lives they had infected, parasitic worms. So they did, for a really, really, really long time. Someone did some rough math on this and came to the conclusion that the Hive have snuffed out around 5,950,000,000,000,000,000 Sentient beings. Did I mention that the Hive, or more accurately the 3 kids, are over 5,000,000,000 years old? Yup, they've been around a minute. Longer than Earth has existed. Also, incase you haven't figured it out by now the 3 kids are Oryx and his 2 other siblings.

During all of their conquesting they ran into what I believe to be the Fallen, aren't called the Fallen, but cut off their arms and grow them back like the Fallen, along the way. The Traveler had uplifted their civilization like it did ours during our Golden Age. Right when Oryx's sister was about to deal the final blow of extinction to the likely to be Fallen race, Oryx pulls a dick move and sucker punches her entire fleet to oblivion for funzees because she left her flank exposed. So what remained of the possibly Fallen bitched out to try and find the Traveler, which bitched out at an earlier point in time during the probably Fallen's fightings with the Hive... Eventually ending up in our solar system.

Oryx and kin eventually figured out that they could cut into other dimensions and keep their soul there. So if they died in the real world, they'd go and chill in their alternate dimension until they felt they could defeat what defeated them. Oryx had a son, Crota as well as 2 daughters. Crota thought it'd be cool to make his own dimension and his aunt said, "go for it bro, cut right here." Turns out his aunt tricked him into releasing the Vex from the other dimension Crota cut into... Crota was in Oryx's dimensional cut and wanted to make his own and cut into another dimension full of the equivalent of robotic space herpes.

So the Vex are wrecking up Oryx's dimensional chillpad bad enough that Oryx goes to try and help. Oryx ends up giving up on trying to get rid of the herpy machines with conventional methods and decides to go consult his not-so-local physician. But, the doc told him he couldn't help with his "issue" so Oryx killed him. Oryx killed one of the Worm gods, kiddos. From doing that he learned how to Take living beings and turn them into glowing black assholes that fight for him, got some kick-ass Dracula wings, and used a part of its body as his own ship... So metal... The first race he extinctifies with his snatch-n-grabbers is the Ecumene, referenced as lords of matter and space. These bad asses were putting the hurt on the Hive until Oryx turned into a body-snatching lobotomiser.

So while Oryx and kin are out murderfacing the universe, the Traveler pops a squat in our solar system, we get super smart, live Gandalf-lengthed lives, make crazy super smart people shit, and populate other planets around our solar system.

Eventually the Fallen find the Traveler followed by the Darkness as well. We fight and die. We die sooooooooo bad. We lose all the planets we've populated and get whittled down to a single city. When this happened the Traveler tried to bitch out again. Rasputin pretty much said fuck that noise, took control of some Golden Age deathrays and blew a hole in that mofo. Kinda like what the Soviets did during WW2 to any of their comrades who tried to run away.

From that hole burst a massive wave of light that pushed the darkness halfway back into our solar system. Where the Darkness and Light met, resulted in the Awoken, which were humans trying to escape what they thought was the apocalypse.

The Traveler could have chosen to run away after it got shanked by Rasputin, but chose to stay since the Darkness would more than likely be able to catch up with it now. It created the Ghosts as a way to fight the Darkness and other races that were trying to kill the earth-folk and inevitably, the Traveler.

Well the rest you should know now. You don't die because you got your Ghost and you can't be Taken because you're already dead. We are pretty much the invincible white blood cells of our solar system, with the Traveler being the solar system's heart.

We still don't know enough about the Cabal except they are running from something. Running fast enough to Troy Polamalu any planets that get in the way.

EDIT: Added a bit to the Fallen part.

EDIT 2: Since many are asking for references I will try to go through and link as much of the sentencing as I can. But most of this can be found by reading the entirety of The Books of Sorrow.

EDIT 3: There were 53 moons, or more accurately XIV: 52 and One

EDIT 4: Crota's Aunt tricked him into releasing the Vex, not his Sisters. See:XI: Conquerors and XXXIX: open your eye : go into it

Edit 5: Further edits to what I believe to be the Fallen as well as Oryx's Taken ability. Ya whiney bastards. This is supposed to be TL;DR!

Edit 6: Spelling, words, clarification.