Ironic (perhaps not), but I’m still to see a society which is not segregated, subtly or emphatically so. When will equal be equal enough, is anyone’s guess. George Orwell had a reason when he wrote,"All animals are equal, but some animals are more equal than others". Brings me to the phrase that has its roots in the same grounds as Ghetto .
"Pale" here refers to the archaic sense of the word when it meant wooden strips that are set in series to form a fence. An area enclosed by them was also referred to as pale. So, to be 'beyond the pale' was to be outside the area that's marked as "territory" or "home". Catherine II created a 'Pale of Settlement' in Russia in 1791. This was a western border region of the country in which Jews were allowed to live. The motivation behind this was to restrict trade between Russian Jews and native Russians. Some Jews were allowed to live, as a concession, beyond the pale. More can be read here .
Pales were enforced in various other European countries for similar political reasons, notably in Ireland (the Pale of Dublin) : that part of the country over which England had direct jurisdiction.
The first printed reference comes from 1657 in John Harington's poem "The History of Polindor and Flostella"
Sources: http://www.phrases.org.uk/, www.answers.com
Pic: Map of "The Pale of Settlement" from http://www.friends-partners.org