Which is replacing the part comes before by which with which? what is such

Othering is a binary process between the colonizer and colonized by which the latter is able to affirm his own identity, but the last is considered as the other

Note that I didn’t use othering, is, between the colonizer and colonized because respectively it’s subject and the auxiliary verb (do,

does, is, has have, am are etc.). The rest just extends the meaning.