Complex sentence: Another original march also developed into one of the most powerful states in Central Europe: the Margraviate of Austria whose rulers, the House of Habsburg, rose to obtain a "de facto" monopoly on election to the throne of the Holy Roman Empire.
Split into simpler sentences: Another original march also developed into one of the most powerful states in Central Europe: the Margraviate of Austria. Its rulers, the House of Habsburg, rose to obtain a "de facto" monopoly on election to the throne of the Holy Roman Empire.