Watch List notes:

ABBASID: al-Mahdi, 775-785, AR dirham (2.91g), al-Yamama, AH168, A-215.1, citing the governor 'Abd Allah b. Sa'id, without the place name Hajar, and with 2 pellets below the obverse field, VF, S. Al-Yamama was the first mint in Arabia to strike silver coins, located near the modern city of Riyadh, with its administrative capital at the town of Hajar. It operated AH165-170.

Estimate: 300-400 USD