Just to augment Mr. Herz's point about how
certain groups are forced into or take on
certain role: some groups go into diaspora
or better, migrate, just to take on roles
that may be advantageous. The migration of
Germans, Walloons, and Flemings into
east-central Europe in the
Middle Ages, or the later movement of
Germans and some Czechs into Russia in
the 18th century comes to mind. From about
the 1100s onward, local rulers in Poland
and perhaps Hungary began inviting Jews
to come and settle. (This movement was
increased in the 14th century as Jews were
expelled from places in western Europe in
the wake of the Black Death.)
In each case, these peoples were invited
in because they had certain skills the locals
did not have. The immigrants were usually granted
relatively broad rights. (Religious freedom,
special courts, and royal protection for the
Jews in Poland, exemption from military
service for the Germans in Russia, etc.)
In each case, it is important to note that
there was an implicit expectation that the
newcomers would not be politically active
and would not seek roles in politics. This
may have been what made groups like the
Jews "safe"--that they would concentrate
on economics and not upset contemporary
political arrangements.
John Radzilowski