The inscription honours two emperors, the first of them being a Marcus Aurelius. This could point to the joint rules of Marcus Aurelius and Lucius Verus (AD 161-169); Marcus Aurelius and Commodus (AD 177-180); or Caracalla (official name Marcus Aurelius Antoninus) and Geta (AD 211).
As suggested by G. Mihailov, this fragment is seemingly the surviving upper part of the lost inscription IGBulg 902, which was observed in the same church (Old St. Petka) and had an identical beginning. If that identification is accepted, the date of the inscription must be set to AD 164-165/6.