This drachm is a wonderful example for the correlation of different cultures. It was issued by Islamic tribes who had overthrown the 'infidel' Sassanian ruling class shortly after the death of their prophet Mohammed. The Sassanians themselves were Zoroastrians and worshipped the god Ahura Mazda.
After their victory over the Sassanids the Islamic tribes adopted Sassanid coinage, initially without any changes; only later did they replace the iconographic motifs by pure scripture. This is why this Islamic coins shows two priests tending the holy fire of Ahura Mazda, a typical Zoroastrian motif.
The obverse bears the portrait of Yazdegerd III, the last Sassanid ruler (632-651). This motif stands in the tradition of Hellenism, which Alexander the Great hat once brought into the region of today's Iran, Iraq, and Syria.