'Abbasid Caliphate. Ibrahim b. al-Mahdi. Usurper, AH 201-203 / AD 817-819. AR Dirham (23.1mm, 2.99 g, 2h). Madinat al-Salam mint. Dated AH 202 (AD 817/8). Letters alif and ha (for Ibrahim) below reverse field. SICA 3, 1752; Lowick 1428; Album E225 . Light crease with some resulting weakness. VF. Rare.
Ibrahim b. al-Mahdi was briefly declared caliph in Baghdad during al-Ma'mun's temporary absence from the capital.