that the Sasanian marzbān (march commander) of Beth Aramaye (south-central Mesopotamia) had his seat in the region of Rādhān. After the Arab conquest of the Sasanian Empire (633–654), the fertility of Rādhān greatly impressed several Arab authors. The poet al-Akhṭal praised its fertility in a poem he wrote during a stay there and al-Farazdaq praises its date palms. "What is in Medina is in Medina and what is in Rādhān is in Rādhān" is a saying attributed to Muḥammad, instructing his followers not to covet the fertility of Rādhān. By the ʿAbbāsid period, Rādhān was an administrative district with a governor. Writing in the 10th century, al-Muqaddasī and al-Iṣṭakhrī describe it as belonging to the province of Fars. Its agricultural sector fed Baghdad. According to Ibn Kurdādhbe (d. 912), it was a district (ṭassūj) composed of 19 townships (rasātīq) containing 302 threshing floors producing 4,800 kurrs (about 1.4 million kilograms) of wheat and paying 120,000 waraq (low-value) dirhams in tax to the central treasury each year. The complete succession of ʿAbbāsid governors of Rādhān is not known. The Persian historian al-Ṭabarī records that in 865 its governor was caught embezzling funds. In 897, he records that ʿAlī ibn Muḥammad ibn Abīʾl-Shawārib was appointed qāḍī over Baghdad and the Rādhāns. In 929, Abū Hījā was appointed governor of the Rādhāns and several other places in central Iraq. Ibn al-Athir (d. 1233) describes Rādhān as one of the provinces of the Khurasan Road and gives its northern limit as the Batt canal, the northern branch of the Ḥawlāyā (or Diyālā) canal, connecting the Nahrwān canal to the Tigris. The Nahrwān canal itself was the eastern boundary of Rādhān. Syriac sources likewise describe Rādhān as bound by the Tigris and the Nahrwān canal. Ibn al-Athir records a Khwarizmian incursion into Rādhān in 1225. Nestorian diocese A Nestorian Syriac tradition, recorded by Mārī ibn Sulaymān, says that the Rādhāns (al-rādhānayn) were evangelised by the legendary Saint Mari, one of the Seventy Disciples. A variant of this tradition attributes the evangelisation of the Rādhāns to both Mari and his teacher, Addai. According to this variant, some Jews destroyed the well of Sāvā that the apostles had built. Another legend attributes the construction of some 300 churches and monasteries in the Rādhāns to a certain Helqānā. Syriac sources name Ḥālē (Arabic Ḥawlāyā) as the capital of Rādhān. Abba the Great was said to be a native