Abbasid Governors in the Yemen, Muhammad ibn 'Ali bin 'Isa bin Mahan (201-4 AH/816-9 AD), with his son Abdullah as deputy in San'a, Dinar, 4.01g., without mint name (San'a), dated 201 AH/816 AD, usual formula, but rev., Muhammad above and Abdullah below central legend, apparently the only known specimen, extremely fine, extremely rare