Dulo clan
The Nominalia of the Bulgarian khans states that Tervel belonged to the Dulo clan and reigned for 21 years. According to the chronology developed by Moskov, Tervel would have reigned 695–715. Other chronologies place his reign in 701–718 or 700–721, but cannot be reconciled with the testimony of the "Imennik". The testimony of the source and some later traditions allow identifying Tervel as the son and heir of his predecessor Asparukh, who had perhaps died in battle against the Khazars.