The etymology of the name may derive from Slavic "rada" - council and "gościć", "hostit" - to host, meaning the one who hosts the council. It could have been a personal name, or an acquired title, synonymous with council, assembly, or veche, leader or chieftain.
The Slavs who plundered Greece in 577 may have been under Ardagast leadership.
After a treaty was concluded in 584 between Bayan I and Emperor Maurice, Ardagast raided Thrace penetrating as far as the Long Wall, the Slavs suffered defeats only twice, at Erginia river and Ansinon neighbourhood of Hadrianople by Comentiolus. The Slavs were later driven out of Astica region.
The raid in Thrace in 585 prompted Emperor Maurice to deal with the Slavs - sending an army with commander-in-chief Priscus and infantry commander Gentzon to cross the Danube at Dorostolon (present-day Silistra) and surprise attack the Slavs in their own territory (as the Slavs had long been pillaging the Byzantine Empire). The Army arrived at the Slavic camp at midnight, surprising the Slavs who fled in confusion, Ardagast fell on a tree stump and was almost captured, but luckily he was near a river and eluded the attackers.
Priscus sent his lieutenant Alexander across the Helibakion (Ialomiţa River) to find Slavs who were hiding in the woods and swamps, they failed to burn out the people hiding, but a Gepid Christian who was associated with the Slavs deserted and showed a secret passage after which the army easily captured the Slavs, who according to the Gepid, were spies sent by King Musokios that just heard about the attack on Ardagast.
||Commander of the Slavs
- Relations between the autochthonous population and the migratory populations on the territory of Romania: a collection of studies, p. 198
- History of the Later Roman Empire from Arcadius to Irene, p. 144
- History of the Later Roman Empire from Arcadius to Irene, p. 119
- Balkan studies: biannual publication of the Institute for Balkan Studies, Volume 37, p. 48
- History of the Later Roman Empire from Arcadius to Irene, p. 128
- History of the Later Roman Empire from Arcadius to Irene, p. 129