For 10 points, name this Muscovite prince who laid the foundations for the empire built by his eponymous "terrible" grandson.
He introduced the pomestie system which granted estates to nobles in exchange for loyalty to the crown. He married Zoë Palaeologus, niece of the fallen emperor of Byzantium, and eventually gave in to her intrigues with Lithuania by naming her favorite son Vasily heir. He conquered Tver, Novgorod, and parts of present-day Ukraine, but his most important move may have been an alliance with the Crimean Tatars which allowed him to repudiate tribute to the Golden Horde. For 10 points, name this Muscovite prince who laid the foundations for the empire built by his eponymous "terrible" grandson.
He introduced the pomestie system which granted estates to nobles in exchange for loyalty to the crown.
{Ivan III} [or {Ivan Vasilyevich}; or {Ivan the Great}; or {Ivan Veliky}; prompt on {Ivan}]