Mamikonian, or Mamikonean, was an aristocratic dynasty which dominated Armenian politics between the 4th and 8th centuries. They were the most notable noble house in Early Christian Armenia after the ruling Arsacid dynasty and held the hereditary positions of sparapet and dayeak, allowing them to play the role of kingmaker for the later Armenian kings. They ruled over extensive territories, including the Armenian regions of Tayk, Taron, Sasun, and Bagrevand, among others. The Mamikonians had a reputation as supporters of the Roman Empire in Armenia against Sasanian Iran, although they also served as viceroys under Persian rule. Their influence over Armenian affairs began to decline at the end of the 6th century and suffered a final, decisive blow after a failed rebellion against Arab rule over Armenia in 774/75.