Northwest Germanic is a proposed grouping of the Germanic languages, representing the current consensus among Germanic historical linguists. It does not challenge the late 19th-century tri-partite division of the Germanic dialects into North Germanic, West Germanic and East Germanic, but proposes additionally that North and West Germanic remained as a subgroup after the southward migration of the East Germanic tribes, only splitting into North and West Germanic later. Whether this subgroup constituted a unified proto-language, or simply represents a group of dialects that remained in contact and close geographical proximity, is a matter of debate, but the formulation of Ringe and Taylor probably enjoys widespread support: There is some evidence that North and West Germanic developed as a single language, Proto-Northwest Germanic, after East Germanic had begun to diverge. However, changes unproblematically datable to the PNWGmc period are few, suggesting that that period of linguistic unity did not last long. On the other hand, there are some indications that North and West Germanic remained in contact, exchanging and thus partly sharing further innovations, after they had begun to diverge, and perhaps even after West Germanic had itself begun to diversify.