 After the surprise death of Malamir in 836, the Bulgarian throne passed to Presian I (836–852), who too was likely underage.As evidenced by the Presian Inscription from Philippi, Isbul retained his position as "kavhan" and his decisive influence in the Bulgarian court.In 837, the Slavic tribe of the Smolyani ("Smolenoi"), who inhabited the lower Nestos (Mesta) River and Western Thrace near Drama, rose against their Byzantine rulers.