'Abbasids
al-Ma'mûn, 195-218 H./811-833 AD Small drachm in the weight of a Tabari-dirham 204 H., Urmiya or rather a misspelt Armînîya, with the names of the governor of Armenia, Ahmad ibn Yahya ibn Mu'âdh and the official Ba'îth ibn Halbas, both only indicated by their ism (proper name). 1.80 g.; Probably unique Very fine Marginal flan crack
Around the year 200 H. various experiments were made replacing the dirham of 2.97 g by the traditional Sasanian drachm weight of 4.1 g and also fractional coinage, both half dirhams (e.g. Vardanyan 207) and half drachms were occasionally struck. The present half drachm seems underweight, but 1.8 g corresponds to the half drachms of Tabaristan circulating widely in Armenia. The special small reverse dies render the shortened versions of the names, while the full dirhams have these names including the patronym. See also Lutz Ilisch, Ungewöhnliche Nominale zur Zeit des al-Ma'mûn, in Jahresbericht 1997 der Forschungsstelle für Islamische Numismatik, Tübingen 1998, p. 9-10.