Complex sentence: The historical predominant language of the much of Alsace is Alsatian, a bunch of Allemannic dialects closely related to Swabian and Swiss German, but after World War II most Alsatians move to primarily speak French, the official language of France.
Split into simpler sentences: The historical predominant language of much of Alsace is Alsatian, a set of Allemannic dialects closely related to Swabian and Swiss German. After World War II, most Alsatians began to primarily speak French, the official language of France.