Watch List notes:

ABBASID: al-Mahdi, 775-785, AR dirham (2.90g), al-Yamama, AH166, A-215.1, inscribed hajar below the reverse field, bold strike, VF-EF, 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: 350-400 USD