Although Germanic is clearly a branch of the Indoeuropean (IE) language, it contains a rather large number of roots that are of non-IE origin. There is some speculation that many words that have to do with the sea, e.g. 'ship' or the names of many species of fish are not IE.

It is possible that Germanic was formed as a result of the interaction between an IE-speaking people and a non-IE one. The non-IE may have lived by the sea. This sea was probably the Baltic. There are also traces in Prussian, a member of the Baltic branch of IE of the influence of a non-IE language.