to Persia's earlier opponents (the Roman Republic and the Roman Empire); the Byzantine Empire. The Sassanids ruled for 425 years, until the Muslim armies conquered the empire. Afterward, the Persians started to convert to Islam, this making it much easier for the new Muslim empire to continue the expansion of Islam. Persis then passed hand to hand through numerous dynasties, leaving behind numerous historical and ancient monuments; each of which has its own values as a world heritage, reflecting the history of the province, Iran, and West Asia. The ruins of Bishapur, Persepolis, and Firouzabad are all reminders of this. Arab invaders brought about a decline of Zoroastrian rule and made Islam ascendant from the 7th century. See also Fars Province Pars (Sasanian province) Persian Gulf Fars (territory) References Ancient Persia History of Fars Province Historical regions of Iran Greek words and phrases