Mass Effect - The Collector War
A race of sentient AIs, the geth were created by the quarians more than three centuries ago. After the geth began to question their sentience, the quarians panicked and attempted to destroy the geth. This conflict, referred to as the Geth War, drove the quarians into exile.
The geth did not follow the quarians, instead remaining behind the Perseus Veil for the past three hundred years. The geth have never, as far as anyone knows, had peaceful contact with any organic races aside from the partnership with the turian rogue Spectre, Saren.