9th-century Christianity

Paulicianism (Classical Armenian: Պաւղիկեաններ, ; , "The followers of Paul"; Arab sources: Baylakānī, al Bayāliqa ) was a Christian sect which originated in Armenia in the 7th century. Followers of the sect were called Paulicians and referred to themselves as Good Christians. Little is known about the Paulician faith and various influences have been suggested, including Gnosticism, Marcionism, Manichaeism and Adoptionism, with other scholars arguing that doctrinally the Paulicians were a largely conventional Christian reform movement unrelated to any of these currents.

posthumous ecclesiastical trial of Pope Formosus

Pseudo-Isidore is the conventional name for the unknown Carolingian-era author (or authors) behind an extensive corpus of influential forgeries. Pseudo-Isidore's main object was to provide accused bishops with an array of legal protections amounting to de facto immunity from trial and conviction; to secure episcopal autonomy within the diocese; and to defend the integrity of church property. The forgeries accomplished this goal, in part, by aiming to expand the legal jurisdiction of the Bishop of Rome.

spread of Christianity in Scandinavia between the 8th and the 12th centuries

spread of Christianity in medieval Moravia

Series of synods held at Aachen between 816 and 819

aspect of papal history