The implication is ingroup vs outgroup as immutables. Aparthiad South Africa had some darkly hillariously arbitrary (no pun intended) definitions of black and

The implication is ingroup vs outgroup as immutables. Aparthiad South Africa had some darkly hillariously arbitrary (no pun intended) definitions of black and white such that Japanese were white and Chinese were once black. Roman identity also fits within the ingroup-outgroup frameworm but not quite immutable. It involved such odd priorities by modern standards like retiring a "gaulic stereotype" class of gladiators after the conquest of Gaul because they were Roman now, even if many were slaves it became "politically incorrect".