On the very edge of the Milky Way galaxy lay the Perseus Veil, a vast nebula of gas and dust that housed the home system of the quarians. Driven from their homeworld of Rannoch centuries ago, the quarians were forced to live a nomadic life, drifting throughout the galaxy in a flotilla composed of thousands of ships. In 2186, they successfully retook Rannoch and achieved peace with the geth with the help of Commander Shepard.

Over the past two decades, the quarians had peacefully coexisted with the geth, establishing basic settlements upon the homeworld which then blossomed into cities of towering constructs.

However, development on this scale came at a cost, and the barren earth of Rannoch had given all it had. With the planet's resources drained the two races set out into the galaxy in search of precious metals and minerals.

The symbiosis of geth and quarian technology resulted in the invention of advanced deep-space mineral scanners, which were then installed upon a fraction of the Migrant Fleet's vessels. These ships were then tasked with retrieving resources from uninhabited planets or asteroids; some were even sent into the unexplored depths of dark space, now free from the Reaper threat.

Some ships returned with their cargo holds bulging with harvested minerals and the occasional vessel would return with a couple crates of element zero. Some ships did not return at all; swallowed up by the void of space.

Power then became an issue in the quarian-geth society. Minerals and construction materials were in abundance but with local supplies of element zero running low and only the occasional shipment coming in from the expeditions, the quarian Conclave and Admiralty were driven to desperate measures. Tens of hundreds of ships were grounded, their element zero stores transferred to the most successful expedition ships. These ships were then sent out again with their primary objective to retrieve element zero.

With element zero being so rare, and with most deposits being dangerously close to supernovas, the ships that were not as well equipped had to resort to scavenging asteroid fields and what little deposits they could find on planets.

Desperate not to return to Rannoch empty-handed, some even ventured into the very edge of the galaxy, hoping for a miracle.