The article is dedicated to the lost chronicle of the Julian’s war of 363 with Persia, written by a Mazdean priest in the second half of the 4thcentury. The text was used by Armenian historian Movsēs Ḥorenac’i whocalled its author by name Ḥoṛohbūt. He is called ‘secretary of Shahpuhrconverted to Christianity’. However, Movsēs did not go into further detailsabout the text, he only mentioned another Persian man, Rastohun, who alsobecame a Christian. It is proposed in search for the remains of the ‘Chronicle’in the Christian East to consider the last part of the s. c. ‘Julian Romance’,written in the 6th century in the Western Syrian milieu. In this text a Mazdean priest and secretary of Shahpuhr by name Arimihr is mentioned. He converted to Christianity and became a friend of the Christian Roman general Jovian (inthe Romance he is called Yoḇı̄nyanōs). Arimihr could be the same figure as Ḥoṛohbūt. There in another echo of the ‘Chronicle’ in the Syriac tradition: inthe ‘Chronicle of Siirt’, which used the ‘Romance’. Later al-Ṭabarı̄ and al-Nadı̄m also used the ‘Romance’ as a source for the story of Julian’s war in Persia. The following reconstruction is proposed: the mobed Arimihr conver-ted to Christianity and returned with the Roman army to Asia Minor. There,after the death of his patron, emperor Jovian, Arimihr wrote his ‘Chronicle’,probably in Syriac. In the beginning of the 6th century it has been included into the hagiographic romance, one copy of which has been sent to Egypt, while another one remained in Mesopotamia and was used by the historian of Siirtand later by ibn al-Kalbı̄, source for al-Ṭabarı̄, before it has vanished. The textof the ‘Chronicle’ was brought to the Caucasian area before it has also dis-appeared. It is corroborated by its mention in the ‘Life’ of the Georgian king Vaḥtang Gorgasal.