Prince Yaroslav continued the main work of the life of his father, Vladimir the Great, “gathering” ancient Russian lands. He restored the unity of Kievan Rus, strengthened the state apparatus, laid the foundations of the judicial system and carried out cultural transformations. It was under him that Kievan Rus became the largest state in Europe. All this gives historians reason to claim that the reign of Yaroslav, nicknamed the Wise, was the time of the highest prosperity of Kievan Rus.