At the same time, naval innovations led to a German domination of trade in the Baltic Sea and parts of Eastern Europe through the Hanseatic League. Along the trade routes, Hanseatic trade stations became centers of the German culture. German town law (Stadtrecht) was promoted by the presence of large, relatively wealthy German populations, their influence and political power. Thus people who would be considered "Germans", with a common culture, language, and worldview different from that of the surrounding rural peoples, colonized trading towns as far north of present-day Germany as Bergen (in Norway), Stockholm (in Sweden), and Vyborg (now in Russia). The Hanseatic League was not exclusively German in any ethnic sense: many towns who joined the league were outside the Holy Roman Empire and a number of them may only loosely be characterized as German. The Empire itself was not entirely German either. It had a multi-ethnic and multi-lingual structure, some of the smaller ethnicities and languages used at different times were Dutch, Italian, French, Czech and Polish.
What other ethnicities, besides German were part of The Empire?
Dutch, Italian, French, Czech and Polish