 Though most of the Palaiologan era was defined by decline and war, it was also an age of cultural flourishing, beginning in the late 13th century.Advances in science and the arts, referred to as the Palaiologan Renaissance, lasted throughout the dynasty's rule, encouraged by the efforts of some emperors such as Andronikos II and Manuel II.By the 15th century, the Byzantine emperors had lost any real power, with the Ottoman sultans increasingly becoming the real regulators of political matters within the empire.