Watch List notes:

Rassid (2nd period), al-Mahdi Ahmad, 'Mahdawi' Dirham, al-Mawqar 646h, 1.88g (Lowick -; A 1085). Very fine and of the highest rarity, believed to be the first recorded coin of this mint.
Smith (1978), p.181, states that al-Mawqar was a place in the vicinity of Hajjah (northwest of San'a).

Estimate: £400-500