Under the banner of Islam, proclaimed by Muhammad (571-632), the Arabs conquered Byzantine Syria and Egypt and the Sasanian Empire under the first four Orthodox Caliphs. The Umayyad Caliphs (661-750) extended Muslim power from the Indus to the Atlantic. Early Islamic coinage imitated the Sasanian silver drahm (dirham in Arabic) and the Byzantine gold solidus and copper follis (dinar and fuls in Arabic). In 696, Caliph Abd-al-Malik struck the first Muslim gold dinars and silver dirhams bearing religious inscriptions-the pattern for most subsequent Muslim coinage.