Like most grand theories of history most of this is only works as a result of approximation. For example, the Unification stuff appears to me to be pure garbage. There is no moment in history when people went from cleanly separating outsiders from insiders. The examples given are both wrong; Egypt was likely ruled by a dynastic elite that came from outside (a common pattern across many cultures in Asia throughout history); the Romans, ironically, are the ones who gave us the word "barbarian". People still rail about foreigners; cf. Brexit.
