Brief Sangheili Snippet of Info:

The Sangheili are biologically identical to their description in the Halo canon. But their history is a bit different, replace all instances of Forerunner in their history with Prothean, and remove the rest of the Covenant, and it's basically complete.

Sangheilian First Contact was bloody, similar to humanity, but peace was called, diplomacy was made, and now the Sangheili are the newest sentient species on the galactic stage, or at least, newest for now. Sangheili have been in the galactic community for three hundred years.