Saeculum obscurum
Saeculum obscurum (Latin: the Dark Age) is a name given to a period in the history of the Papacy during the first half of the 10th century, beginning with the installation of Pope Sergius III in 904 and lasting for sixty years until the death of Pope John XII in 964. During this period, the Popes were influenced strongly by a powerful and corrupt aristocratic family, the Theophylacti, and their relatives.
Periodization
The period was first identified and named by the Italian Cardinal and ecclesiastical historian Caesar Baronius in his Annales Ecclesiastici in the sixteenth century. Baronius' primary source for his history of this period was Liutprand of Cremona. Other scholars have dated the period more broadly or narrowly, and other terms, such as the Pornocracy (German: Pornokratie, from Greek pornokratiā, "prostitute rule") and the Rule of the Harlots (German: Hurenregiment), were coined by Protestant German theologians in the nineteenth century.
Historian Will Durant refers to the period from 867 to 1049 as the "nadir of the papacy".