Tiridates III, also known as Tiridates the Great or Tiridates IV, was the Armenian Arsacid king from c. 298 to c. 330. In the early 4th century, Tiridates proclaimed Christianity as the state religion of Armenia, making the Armenian kingdom the first state to officially embrace Christianity.

Diocletian, nicknamed Jovius, was Roman emperor from 284 until his abdication in 305. He was born Diocles to a family of low status in the Roman province of Dalmatia. Diocles rose through the ranks of the military early in his career, eventually becoming a cavalry commander for the army of Emperor Carus. After the deaths of Carus and his son Numerian on a campaign in Persia, Diocles was proclaimed emperor by the troops, taking the name Diocletianus. The title was also claimed by Carus's surviving son, Carinus, but Diocletian defeated him in the Battle of the Margus.