The “filth of others” can be described in as many ways as a human might use to justify their elevation of one tribe over the degradation of another.

Look at it critically - whenever you encounter a totalitarian-authoritarian personality bloviating about “those people over there” (others), its usually based on the totalitarian mechanism of ‘avoiding affinity with attributes considered unsavoury’ (filth).

This concept has other applications. If you have two villages, separated perhaps by a near-insurmountable mountain or lake, or if one of those villages raises cows while the other raises goats - this is usually the basis of the formation of a new dialect, accent, or indeed entirely new language. However, when civilization occurs and those two villages merge into a broader community, that language changes to become a unity.

This is observable at an individual level, too. Any unacknowledged or under-recognized similarities/identities/differences between two or more entities will inevitably be used to justify segregation of those entities. The solution, as always, is to identify similarities/identities/differences in a cohesive manner - this is anathema to the totalitarian-authoritarian personality, who is usually pretty stubborn about enforcing, in totality, those under-acknowledged facets.