The colonial period, roughly between 1600 and 1900, saw an unprecedented movement of speakers of English to locations overseas. The reasons for this movement vary considerably, from deportation of prisoners and political opponents to voluntary emigration by groups with economic motives, sometimes mixed with religious ones. The rise of first-language overseas varieties depends heavily on the founder generation and the sociolinguistic scenarios they found themselves in. In addition, many countries have second-language varieties which in general have arisen through an English-oriented educational system and, previously, through contact in colonies with English speakers.

Recent discussions around the genesis of varieties of English have posed the question of whether there are certain types which in principle form a typological class (e.g. creoles). Relatively little attention has been paid to shift varieties of English, which in terms of the sociolinguistics of language contact and development form a distinct group. When a group shifts to a language it is in contact with, features can be transferred into a new variety of that language which, if maintained by later generations, form a new, focused variety of the target language.