 The earliest record of Isbul is the stone epigraph known as the Malamir Chronicle, which states that Malamir "ruled together with "kavhan" Isbul".Malamir was the youngest son of Omurtag and must have been considered too young to rule by himself, so that a regent had to be appointed.Omurtag specified Malamir as his heir because his eldest son, Enravota, was a Christian.