A possibly unique Umayyad dinar dating to 91H / AD 709-710 will headline Morton & Eden's Islamic coin auction on April 10 in London.
It is valued in excess of £300,000 ($494,670).
The Umayyad caliphate was an early Islamic empire that spanned the Middle East, north Africa and southern Spain between AD 661 and 750.
Whether unique or not, it is the first time a 91H specimen has appeared at auction. Examples from other years have performed exceptionally well previously, with a dinar produced in 92H selling for £648,000 ($1m) and another made in 105H achieving £3.7m ($6.1m).
The present example was minted from the personal gold mine of the caliph and features the inscription "Mine of the Commander of the Faithful" - which only appears on a tiny subset of coins from the era.
An Umayyad dirham of Tokharistan, thought to have been produced in 80H (AD 699), is valued at £50,000 ($82,470).
The coin is the only known example to have been minted in the town, which stood on the outskirts of Balkh in modern day Afghanistan.
It was produced during the Muslim conquests at a time when the empire was expanding to the east. It bears four pellets in the margins, a feature that does not appear on any other coin from the era.
Later pressings would feature five pellets as standard.
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