Yuhanna ibn Shay Allah belongs to the family of the priest Abu al-Karam, originally from Bartulli. His father is Shay Allah son of Sa'd al-Din, who is also nicknamed Ibn al-Asfar.

Yuhanna Bar Shay Allah was born at Mardin in 1442 and studied Syriac literature under the priests Shamoun of Amid and Yuhanna of Mardin as well as the monks Yeshu of Basibrin and Dawud (David) bar Qashafo of Qalat al-Mar'a . He also studied astronomy, dialectics, philosophy and also theology in Mardin, Syria and Egypt.

He was ordained a bishop of (Sawro) al-Sawr near Mardin in 1471 and was elevated to the patriarchal throne in 1483 with the name Ignatius Yuhanna XIII. He died in his middle age in 1493, after having ordained fourteen metropolitans and bishops. HH the Patriarch Ignatius Ephrem Barsoum found a few lines of verse of his in the heptasyllabic meter, expostulating his friend the monk Dawud of Homs. In 1496 an anonymous writer who may be one of his disciples or a relative wrote his life story in eighteen pages in a correct but rather involved and ungraceful style.

(History of Syriac Literature and Sciences, Patriarch Ignatius Ephrem I Barsoum, Presseggiata Press, p 165)