Athanasius IV of Salh, belongs to Salhiyya, not Salah. His name was Lazarus. He assumed the monastic habit and also studied at the Monastery of Mor Aaron, known as the Shaghr (ܥܘܡܪܐ ܕܡܪܝ ܐܗܪܘܢ ܕܫܓܪ̈ܐ), where he became reputed for wisdom and piety.

He was consecrated a patriarch on Thursday October 21, 986, and resided at the Barid Monastery, which he rebuilt and embellished.

He died in 1002 at the monastery of Mor Barsoum, after he had ordained thirty-nine metropolitans and bishops, and Mapheryono (Catholicos) Bar Qiqi.

In the year 1000, he compiled and assigned the lectionaries from both Testaments to be read in the Church; his selections indicate utmost taste and arrangement.