Mor Dionysius Telmaharoyo (of Tell-Mahre), Patriarch of Antioch, was a great and unique church dignitary deeply versed in knowledge. He was born at Tall-Mahre near al-Raqqa on the Balikh, to a noble and wealthy Eddessene family and became famous at the beginning of the seventh century for his great contribution to the church of Edessa.

At Qinnesrin he studied philology, jurisprudence, philosophy and theology and entered the monastic life. He spent his earlier years as a monk at the convent of Qinneshrin on the upper Euphrates; and when this monastery was destroyed by fire in 815, he migrated northwards to that of Kaisum in the district of Samosata. At the death of the patriarch Kyriakos in 817, the church was agitated by a dispute about the use of the phrase heavenly bread in connection with the Eucharist. An anti-patriarch had been appointed in the person of Abraham of Qartamin, who insisted on the use of the phrase in opposition to the recognized authorities of the church.

It is sufficient to mention that in summer 818 forty-eight metropolitans and bishops who met in Al-Raqqa unanimously elected him for the Apostolic See as a successor to patriarch Kyriakos, while he was still an initiate monk, Sorely against his will he was brought to Raqqa, ordained deacon and priest on two successive days, and raised to the supreme ecclesiastical dignity on August 1. From this time he showed the utmost zeal in fulfilling the duties of his office, when he headed the Church, he adorned his high office with his piety, honest belief, deep understanding, wide knowledge and firm will. For twenty-seven years he administered the affairs of the Church with great energy, discerning policy, sound judgment, and graceful patience. He held three councils at Callinicus in 818, another council at Euspholos in 828 and another at Takrit in 834. He also issued canons and ordained a hundred metropolitans whose names are cited by Michael the Great.

Undertook many journeys both within and without his province. The ecclesiastical schism continued unhealed during the thirty years of his patriarchate. He visited the Caliph al­Mamun in Baghdad and Egypt three times and paid one visit to the Caliph Mu'tasem, who recognized his caliber and high position, and chose him for a political mission. Also, he was respected and recognized by the prince (Amir) Abdullah ibn Tahir al-Khuza'i. The former was the most famous of the Abbasid Caliphs in judiciousness and knowledge. The latter was the best of the Amirs in character, chivalry and justice; he rebuilt the churches which had been unjustly destroyed. The details of this contest, of his relations with the caliph Al-Mamun, and of his many travels including a journey to Egypt, on which he viewed with admiration the great Egyptian monuments, are to be found in the Ecclesiastical Chronicle of Bar-Hebraeus.

After leading a dignified life, but one bothered by sufferings inflicted on his people by the unjust rulers, he died on the twenty-second of August, 845. his last days having been especially embittered by Mahommedan oppression.

Mor Dionysius Telmaharoyo was the author of an important historical work, which has seemingly perished except for some passages quoted by Bar-Hebraeus and an extract found by Assemani in Cod. Vat. 144 and published by him in the Bibliotheca orientalis (ii. 7277).

We learn from Michael Rabo the Syrian that one of his writings is magnificent Annals, covering the period from 583 to 843, which he compiled at the request of john, metropolitan of Dara. It consists of two volumes, each divided into eight treatises, which in turn are divided into chapters, covering the events of a period of 260 years, viz, from the accession of the emperor Maurice (582-583) to the death of Theophilus (+843).  Michael the Great utilized the Annals to a great extent and enriched his history, by incorporated Dionysius' introduction in its entirety to it. He also added to it the events of these Annals in brief. The original copy of these Annals was lost, except for two or three chapters, but its compendious has survived. The Annals of Dionysius also contains an interesting description of the pyramids, as well as the conditions of the Coptic Church which welcomed him, and his acceptance by the patriarch Jacob and his bishop outside the city of Tannis in 833. These accounts were incorporated by Bar Hebraeus into his Ecclesiastical History. It was mentioned before that Assemani had erroneously ascribed to Dionysius the history written by the monk of Zuqnin. Finally, Dionysius issued twelve canons at the council of Callinicus, preceded by a distinguished proclamation immediately after his consecration.

(See also: History of Syriac Literature and Sciences, Patriarch Ignatius Ephrem I Barsoum, Presseggiata Press, p 127)