Geth learned the history of the Humans in this world through the eyes of the Slime. Page after page of the world's history flashed before him as Ro-Zek read through the tomes.
The initial merge was just as dangerous as Geth remembered through his dreams. Many Humans died, along with many of the other Races due to the devastation the expansion of the planets caused.
Somehow, in this timeline, many of the Human military bases survived. This included their weaponry, vehicles, and adequately defensible places to bunker down.
With these advantages, the Humans swiftly conquered the areas surrounding these military bases. At first, it was fear of the unknown and a primal need for survival.
However, it didn't take long for them to find that they became more powerful after every kill. The Human Race banned together to capture and study the other Races as they tried to find a way to counter some of the stronger beings.