In 1971, when the Shah of Iran held a great celebration in Persepolis to commemorate the 2,500th anniversary of the foundation of the Persian monarchy by Cyrus the Great, he was vehemently attacked on Islamic religious grounds. Exalting the monarchy was bad enough, but far worse was the proclamation of a common identity with the Zoroastrian past, and a consequent redefinition of the basis of allegiance. For the shah's religious critics, the identity of the Iranians was defined by Islam, and their brothers were Muslims in other countries, not their own unbelieving and misguided ancestors.