Perhaps from Symeon Metaphrastes, opined Adler, who also noted that Jonathan Toup (1713-1785) suggested *persw=n ("of Persians") for the transmitted pate/rwn. Any necessity for emendation, however, is arguable, given the fact that both of these phrases are well-attested separately and need not be supposed to be presented here as a single one. "Boundaries of nations", in particular, comes from Deuteronomy 32.8.
For o(/rion, see generally omicron 564.