The Principality of Khachen (Armenian: Խաչենի իշխանություն, romanized: Khacheni ishkhanutyun) was a medieval Armenian principality on the territory of historical Artsakh (present-day Nagorno-Karabakh). The provinces of Artsakh and Utik were attached to the Kingdom of Armenia in antiquity. In the early medieval period, these provinces were under Sassanid or Arab suzerainty until the establishment of the Bagratid Kingdom of Armenia in the 9th century. From the 12th century the Armenian Principality of Khachen dominated the region. The Byzantine emperor Constantine VII addressed his letters to the prince of Khachen with the inscription "To Prince of Khachen, Armenia."