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.
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.