The Grand Dukes of Moscow were powerful rulers in Russia from the late 13th century until the early 16th century. They played a crucial role in unifying various Russian principalities and laying the foundation for the future Russian state. The title "Grand Duke" signified their authority over other dukes and their leadership in the region. One of the most notable Grand Dukes was Ivan III, also known as Ivan the Great, who expanded Moscow's territory and ended Mongol dominance. His grandson, Ivan IV, or Ivan the Terrible, became the first crowned Tsar of Russia, marking the transition from the Grand Duchy to the Tsardom of Russia.