On their coins, the Byzantine rulers settled on the second place since the end of the 7th century. Like on this tetarteron dating from to the rule of Emperor Constantine IX Monomachos (1042-1055), Christ as the world ruler was depicted on the obverse. The Byzantine ruler, being the "servus Christi" (Christ's servant), contented himself with the reverse of the coin. The tetarteron was introduced around the middle of the 10th century, probably in alignment with the dinar of Fatimid Egypt. The new coin was somewhat lighter and had a smaller diameter than the traditional Byzantine gold coin, the solidus. From now on the solidus was called histamenon, meaning more or less "standard."