 At the same time, according to Constantine VII's work "De Administrando Imperio" (10th century), a group of Croats separated from the White Croats who lived in White Croatia and arrived by their own will, or were called by the Byzantine Emperor Heraclius (610-641), to fight and defeat the Avars after which they eventually organized their own principality in Dalmatia.With the death of Samo, some Slavic tribes again came under Avar rule.The Bulgar Khan Kubrat died in 665 and was succeeded by Khan Batbayan of Old Great Bulgaria.