Universal varnas?

[Martin Gansten]

Modern advocates of (Neo-)Hinduism sometimes argue the merits of the
four-varna system on the basis of its supposed universal applicability: the
division of society into an intellectual, a ruling, a productive, and a
serving class is claimed to be a fact all over the world, which fact the
varna system merely recognizes and conforms to. Is anyone aware of similar
views having been expressed in classical Hinduism (whatever that means!)? In
other words, did any traditional Hindu authors conceive of non-Indian races
and nations as divided into four varnas or varna-like groups? -- and if so,
how did these compare to the domestic varieties in terms of purity etc?

Regards,
Martin Gansten