Photo: Jack Guez, AFP/GETTY

Six sport divers from a local club were scuba diving in the ancient Roman harbor of Caesarea in Israel, when one of them spotted a small tiny coin, which the diver thought looked like a toy coin from a game of some sort. On further examination, the coin turned out to be gold. Then the divers found another and then another. Later using a metal detector, they found a cache of 2,000 gold coins of various dimensions and weights. The gold coins, most dating from the Fatimid caliphate that ruled much of the Mediterranean from A.D. 909 to 1171, are the largest treasure of gold coins ever discovered in Israel.

As reported by National Geographic: At its height in the mid-tenth to mid-eleventh centuries A.D., Fatimid rule stretched across North Africa and Sicily to the Levant, with trade ties that extended all the way to China. From its capital in Cairo, the caliphate controlled access to gold from sources in West Africa to the Mediterranean, and the currency crafted from the precious metal conveyed the Fatimids’ formidable power and wealth.

A cursory study reveals that the earliest coin from the hoard was minted in Palermo, Sicily, while the majority came from official Fatimid mints in Egypt and other parts of North Africa and date to the reigns of Caliphs al-Hakim (A.D. 996-1021) and his son al-Zahir (A.D. 1021-1036). The coins are of two different denominations—whole dinars and quarter dinars—and are of various weights and sizes. Initial tests indicate that they are 24-karat gold with a purity of upwards of 95 percent.

Now researchers must figure out why such a large amount of currency was found on the seafloor so far off the coast. Sharvit is confident that the hoard is from a shipwreck and suggests several scenarios, including that the coins belong to a merchant ship or may be associated with a tax payment on its way to Cairo.

Thanks to Alaric Bond for contributing to this post.