1 Answer

A diaspora (from Greek διασπορ?, "scattering, dispersion")is "the movement, migration, or scattering of people away from an established or ancestral homeland"[2] or "people dispersed by whatever cause to more than one location",[3] or "people settled far from their ancestral homelands".
The word has come to refer to historical mass-dispersions of people with common roots, particularly movements of an involuntary nature, such as the expulsion of Jews from the Middle East, the African Trans-Atlantic slave trade, the southern Chinese during the coolie slave trade, or the century-long exile of the Messenians under Spartan rule.
Recently, scholarship has distinguished between different kinds of diaspora, based on its causes such as imperialism, trade or labor migrations, or by the kind of social coherence within the diaspora community and its ties to the ancestral lands. Some diaspora communities maintain strong political ties with their homeland. Other qualities that may be typical of many diasporas are thoughts of return, relationships with other communities in the diaspora, and lack of full assimilation into the host country.

http://en.wikipedia.org/wiki/Diaspora