Mass Effect contains a lot of different races that inhabit the Milky Way, and each one has a rich and unique history. However, since players see the game from the point of view of a human, they aren’t present to witness the events that defined the lives of other races. As a race that joined the rest of the inhabitants of the Milky Way in galactic travel and politics, humans haven’t witnessed many events that shaped the relations and cultures of other races that work with them after first contact was made and the resulting war resolved.

https://screenrant.com/mass-effect-geth-quarians-enemies-explained/