According to the hagiographical Syriac Life of John of Dailam, John was born in Ḥdattā, a town on the confluence of the Upper Zab and the Tigris, in 660 A.D.
One short hagiographical work known as the Vita Fructuosi (Life of Fructuosus of Braga), was from the 16th to the mid 20th century wrongly thought to have been written by Valerio.