At Mahdia, Roger I and William I minted of pure gold, 22 mm in diameter and weighing 4.15 g with inscriptions, probably for internal circulation in Africa. The only two known coins were first discovered by the Tunisian scholar H. H. Abdul-Wahab in 1930. They were a close imitation of a type minted by the (1020–35) over a century earlier. These did not make use of a title, like "king", nor did they name any of Roger's domains, rather they employed language (al-Mu‘tazz bi-‘llāh, "who holds his glory of God") usually reserved by Muslims for the (commander of the faithful). The inscriptions on Roger's known coin are written in two concentric circles with two lines of text in the centre. The circular text is the same on both sides, while the central text differs: "This dinar was struck by order of the most respected [or excellent king] Roger, who holds his glory of God , in the city of Mahdia, in the year 543 ", that is, 1148/49, in the outer circle and "Praise be to God as He merits and as it is right He should be praised" in the inner circle. The centre reads "The King Roger", while the centre reads "He who holds his glory from God". William's coin is dated to 549 (1154/5). It has been observed that the inscriptions bear a resemblance to those of 's struck at Palermo in 1072. In both cases the mint would have been staffed entirely by Muslims.. • The Kingdom of Women by Choo Waihong is published by IB Tauris, £17.99. To order a copy for £15.29, go to bookshop.theguardian.com or call on 0330 333 6846. Free UK p&p on orders of more . The kingdoms of west Africa had diplomatic links and equal trade with Europe. Then the age of empires began.