ISLAMIC, Arabia. Rasulid. al-Mansur 'Umar I, AH 626-647 / AD 1229–1250. Dirham (Silver, 26 mm, 1.82 g, 11 h), type C, Mabyan, AH 636 = 1238/9. Citing the ʿAbbasid caliph al-Mustansir billah (AH 623-640 / AD 1226-1242) within a diamond with excurvate sides, ‘bism Allāh / al-imām al-Mustanṣir / billāh Abū Jaʿfar / al-malik al-Manṣūr / Abu’l-Fatḥ ʿUmar ibn ʿAlī’ (‘In the name of Allah. Imam al-Mustansir billah Abu Jaʿfar. King al-Mansur Abu’l-Fath ʿUmar son of ʿAli’ in Arabic); around, ‘lā / ilāha / illā / Allāh / Muḥammad / rasū/l / A/llāh’ (‘There is no deity but Allah. Muhammad is the messenger of Allah’ in Arabic). Rev. Citing the names of the four Rashidun Caliphs within a diamond with excurvate sides, ‘al-aʾimma al-rāshidūn / Abūbakr al-ṣiddīq / ʿUmar al-fārūq / ʿUthmān dhū al-nūrayn / ʿAlī abū al-sibṭayn’ (‘The rightly guided imams, Abubakr the Upright, ʿUmar the Distinguisher between Truth and Falsehood, ʿUthman the Possessor of Two Lights, ʿAli the Father of the Grandsons [of the Prophet]’ in Arabic); around, ‘ḍuriba / bi Mabyan / sana / sitt / thalā/thīn / sitta miʾa’ (‘Struck in Mabyan in the year 636’ in Arabic). Album 1100.3. Extremely rare. Areas of weakness and with some deposits and a ragged edge, otherwise, extremely fine.