City in upper Mesopotamia and important center of Syriac Christianity, especially for the Syr. Orth. Church as the city closest to Dayr al-Zaʿfarān, the seat of the patr. from 1293 until 1932. Despite its strategic location overlooking the plain to the south at the point where the road from Nisibis to Amid enters the mountains, Mardin seems to have been of relatively little importance in Roman and Byzantine times. In Islamic times, it was the seat of a line of Artuqids from 1108/9 until 1408. Administrative center of a district (sancak) within the province (vilayet) of Diyarbakır in late Ottoman times, Mardin is today the capital of the province of the same name in the Republic of Turkey.

Barsoum mentions as the first bp. of Mardin a certain Christopher named in the Life of Mor Abḥai. Historically more certain is Daniel ʿUzoyo, abbot of Qarṭmin (see Monastery of Mor Gabriel), who was made metropolitan of Tella, Mardin, Dara, and Ṭur ʿAbdin in 614/5. Until the 12th cent., the see of Mardin was frequently joined with that of Kfartuto, apparently with residence at first (until 8th cent.?) in Kfartuto and later in Mardin. In the schism that followed the death of Patr. Philoxenos Nemrod in 1292, Ignatius bar Wahib (patr. 1293–1333) became the first in the line of patriarchs who resided regularly in Mardin and Dayr al-Zaʿfarān. Following the death of Philoxenos Yuḥanon Dolabani in 1969, the see remained vacant and was administered by patriarchal vicars until the appointment of Philoxenos Saliba Özmen in 2003.

Mardin was also an important center of the Syr. Catholic movement and was, along with Beirut, a regular place of residence for the Syr. Catholic patriarchs from 1853, when Metr. Yūliyūs Anṭūn Samḥīrī of Mardin was elevated to the patriarchate, until the First World War.

The presence of E.-Syr. Christians in Mardin is suggested by the inclusion of ‘Mardin’ in the titles of bishops of Maypherqaṭ from the 12th cent. onwards. The first E.-Syr. bp. specifically for Mardin seems to be the Chald. Ḥenanishoʿ consecrated after the schism of 1552. The scholar-bp. Yoḥannan Eliya Mellus (1831–1908, metr. of Mardin since 1890) left an important collection of mss. at the Chald. episcopal residence. The Chald. see of Mardin lapsed with the death of Israel Audo (metr. 1914–41).

In 1913, Tfinkdji estimated the Christian population of Mardin at 20,000 out of a total population of 50,000, with 6,500 Armenian Catholics, 7,000 Syr. Orth., 1,750 Syr. Catholics, 1,100 Chald. and 120 Protestants. In 2005, there were reported to be 75 Syr. Orth., 7 Syr. Catholic, and 2 Armenian families as well as 1 Chald. family.

The following churches are to be found today or are known to have existed in the past in Mardin. Syr. Orth.: 1. Forty Martyrs (in Şar Quarter, west of Cumhuriyet Square, formerly Mor Behnam and Sara, 5/6th cent., principal church of Syr. Orth. community with former patriarchal apartments); 2. Mor Mikayel (south of town, on the site of martyrdom of Michael and his sister, 5th  cent.?); 3. Mort Shmuni (in Teker Quarter in eastern part of old city, 6th cent.?); 4. Mor Peṭros and Pawlos (in Gül Quarter near eastern end of old city, 1914); 5. Yoldat Aloho (in Savur Gate Quarter near eastern end of old city, 1857, sold in 1953). Syr. Catholic: 1. Yoldat Aloho (Immaculate Conception, on Cumhuriyet Square, 1860; the adjacent former patriarchate, built in 1895, is now a municipal museum); 2. Mor Ephrem Monastery (in Diyarbakır Gate Quarter at western end of old city, 1884). Chald.: 1. Mar Hormizd (east of Cumhuriyet Square, 430). Others: 1. St. George (Surp Kevork, former Armenian Catholic cathedral, 420); 2. St. Joseph (Surp Hovsep, Armenian Catholic, 1894); 3. St. Barbara (Armenian Catholic monastery, demolished); 4. ‘Patriye Kilisesi’ (Latin [Capuchin], 1884, demolished); 5. Protestant (demolished); 6. former Forty Martyrs (converted to mosque in 1170, now Şehidiye Mosque); 7. former Mor Yuḥanon (Syr. Orth., converted to mosque in 1950s, now Zeyt Mosque); 8. former Mor Tumo (now Ulu Cami?).

Of the 94 mss. at the Chald. episcopal residence described by A. Scher in 1908, sixteen were donated to the Vatican by Israel Audo, but most of the remainder are believed still to be in Mardin, along with a good number of mss. transferred there from Amid. An important collection of mss. is also to be found at the Syr. Orth. Church of the Forty Martyrs.