Emperor Kastav ruled over the Reman Empire after King Reman I and Emperor Brazollus Dor and before Emperor Reman Cyrodiil II. In the year 1E 2801, Kastav ordered the Dragonguard of Skyrim to seize hostages from Markarth and Hroldan to ensure that the Jarls "meet their conscription quotas." The Master of the Dragonguard at that time protested against this but his protest was denied by the Emperor. The hostages were housed and trained. Later in 1E 2804, Emperor Kastav ordered the Dragonguard to suppress the Winterhold Rebellion but the Master refused to do so. In response, the Kastav ordered for their supplies to be cut off. In 1E 2805, Sky Haven Temple was besieged and the city of Winterhold was sacked by a failed Dragonguard recruit named Kalien. In 1E 2806, Sky Haven Temple learned that Reman II was crowned after the siege was lifted, this means that Kastav must have died and Reman II ordered for the siege to end when he was crowned.