Complex sentence: The league had a fluid structure, but its members shared some characteristics; most of the Hansa cities either started as independent cities or gained independence through the collective bargaining power of the league, though such independence remained limited.
Split into simpler sentences: The League had a fluid structure, but its members shared some characteristics. First, most of the Hansa cities either started as independent cities or gained independence through the collective bargaining power of the League, though such independence remained limited.