Vast in numbers, the Grineer have expanded their vile empire from Earth outward to all sectors of the solar system. Once the Grineer rediscovered cloning technology, they seized control of Earth through sheer numbers.
While they may be at the height of power, the Grineer army is in bodily decay and their features are increasingly primitive as a result of continuous cloning. As such, the Grineer are forced to use technology as a crutch for their genetic deterioration. An ideology of hate and discrimination towards the Tenno continues to drive the Grineer forward in the face of inevitable dissolution.