Феофилакт Симокатта
The "Gusli" is one of the oldest musical instruments that have played an important role in the Russian music culture. Vertkov states that the first mentions of the "Gusli" date back to 591 AD to a treatise by the Greek historian Theophylact Simocatta which describes the instrument being used by Slavs from the area of the later Kievan Rus' kingdom. However, it is not exactly clear what instrument was meant by that word, because in Old Slavic or Old Russian "gusli" was used to refer to any stringed instrument. The first documented gusli were recorded in 1170 in Veliky Novgorod in Novgorodian Rus'. The Greek historians Theophylact Simocatta and Theophan were the first to mention the "gusli". During the war at the end of the 6th century, the Greeks took Slavonic prisoners and found a musical instrument named the "Gusli". This corresponds to what the Arabic authors Al-Masudi and Ibn-Dasta mentioned in the 10th century.