Constantine IV, called the Younger and sometimes incorrectly the Bearded out of confusion with his father, was Byzantine emperor from 668 to 685. His reign saw the first serious check to nearly 50 years of uninterrupted Islamic expansion, most notably when he successfully defended Constantinople from the Arabs, and the temporary stabilization of the Byzantine Empire after decades of war, defeats, and civil strife. His calling of the Sixth Ecumenical Council saw the end of the monothelitism controversy in the Byzantine Empire; for this, he is venerated as a saint in the Eastern Orthodox Church, with his feast day on September 3.

Constans II, nicknamed "the Bearded", was the Byzantine emperor from 641 to 668. Constans was the last attested emperor to serve as consul, in 642, although the office continued to exist until the reign of Leo VI the Wise. His religious policy saw him steering a middle line in disputes between the Orthodoxy and Monothelitism by refusing to persecute either and prohibited discussion of the natures of Jesus Christ under the Type of Constans in 648. His reign coincided with Muslim invasions under, Umar, Uthman, and Mu'awiya I in the late 640s to 660s. Constans was the first emperor to visit Rome since the fall of the Western Roman Empire in 476, and the last one to visit Rome while it was still held by the Empire.