With reports that Ahmadinejad's Iran is about to require Jews to wear a yellow ribbon around their arm and Christians a red one, it's worth remembering that this idea is hundreds of years old:
The battle of Nehavend in 642 A.D. and the defeat of the Sassanid by Arab-Muslims ended the independence of Persia after nearly 12 centuries and it became a part of the Arab-Islamic entity. The Umayyad and Abbasid caliphs of Damascus and Baghdad controlled Persia. Arabic words infiltrated the Persian language, and Islam replaced Zorastrianism as the state religion.
These changes had a profound impact on the many religious minorities within Persia. Through a covenant of Omar (a Sunni Muslim leader), non-Muslims were deprived of social and political equality, and became, in effect, second-class citizens. Jews were made to wear a yellow ribbon on their arms and Christians a blue ribbon to distinguish them from Muslims.
Professor Amnon Netzer of the Hebrew University in Jerusalem told RFE/RL that the yellow patch as a distinctive mark for Iranian Jews reappeared a number of times through Iranian history, most recently at the beginning of the 20th century.
It was only with the coming of the Pahlavi dynasty that Jews were treated as normal citizens in Iran. So, can we thank Jimmy Carter for this?