Cyriades (referred to in other sources as Mareades or Mariades or Mariadnes) was a Roman rebel who betrayed the city of Antioch to Shapur I sometime during the 250s. His chief claim to fame is that he is enumerated as one of the Thirty Tyrants who supposedly tried to overthrow the emperor Gallienus. The Historia Augusta Cyriades is listed first in the catalogue of usurpers that comprise the chapter on the Thirty Tyrants within the notoriously unreliable Historia Augusta (and writing under the fictitious name of Trebellius Pollio), whose narrative is brief, indistinct, and largely inaccurate. According to this source, Cyriades was the son of a rich man, also named Cyriades, and whose debauched lifestyle offended his father. After stealing from his father, he fled to the Persians, stimulated Shapur I to invade the eastern Roman provinces and helped in the capture of Antioch and Caesarea. At this point he assumed the purple together with the title of Augustus, possibly killing his father before being slain by his own followers after a short, cruel and crime filled reign. The Historia Augusta dates this as occurring when the emperor Valerian was on his way to the east to fight the Persians, so the traditional assumption is that the date of this rebellion was 259. Edward Gibbon instead dated the usurpation as occurring after the defeat and capture of Valerian in 260. Other sources The events of the Persian invasion of the east are also mentioned by other sources, but they attribute the fall of Antioch to the intrigues of an individual named Mareades or Mariades or Mariadnes, none of whom claimed the imperial dignity. Ammianus Marcellinus mentioned that during the attack on Antioch during the reign of Gallienus, "Mareades, who had inconsiderately brought the Persians there to the destruction of his own people, was burned alive." Outside of the reference to Gallienus' reign, Ammianus Marcellinus does not date this event, but some scholars date this to 256. The Anonymous Continuator of Cassius Dio refers to a Mariadnes, and describes the same event, but with some variations. Firstly, the people of Antioch were aware of the upcoming invasion, and that a large part of the population of Antioch remained in the city, being well-disposed toward Mariadnes and also favouring a change from the Romans to the Persians. Since this part of the work immediately precedes a section on the approaching formal recognition