Complex sentence: Germanic placenames were first attested in limitrophe areas settled by Germanic colonisers (with Roman approval) from the 4th to 5th centuries as the Franks settled northern France and Belgium, the Alemanni in Alsace and Switzerland and the Burgundians in Savoie.
Split into simpler sentences: Germanic placenames were first attested in border areas settled by Germanic colonizers (with Roman approval). From the 4th to 5th centuries, the Franks settled in northern France and Belgium, the Alemanni in Alsace and Switzerland, and the Burgundians in Savoie.