A Persian name or Iranian name consists of a given name (Persian: نام Nâm), sometimes more than one, and a surname (نام‌ خانوادگی). Given names Since the Muslim conquest of Persia, some names in Iran have been derived from Arabic, although the majority are Persian in origin. Persian Christians have Arabic names indistinguishable from their Muslim neighbors. They can also use Arabic derivations of Christian names (such as saints' names), or Greek, Neo-Aramaic, or Armenian names, as most Christian Iranians are Iranian Armenians, although there are also Iranian Assyrians and Iranian Georgians. Many Persian names come from the Persian literature book, the Shahnameh or "Epic of Kings". It was composed in the 10th century by Ferdowsi and is considered by many the masterpiece of Persian literature. Approximately 10%-15% of all Persian names are from Shahnameh. A few examples are Abtin, Ardeshir, Armeen, Arzhang, Babak (Papak), Bijan, Bizhan, Bozorgmehr, Darab, Dariush (Darius), Esfandiar/Esfandyar, Javid, Faramarz, Farhad, Fariborz, Farshid, Farzad, Sam and Yazdan. Last names Prior to 1919, the Iranian people did not use surnames. An act of the Vossug ed Dowleh government in 1919 introduced the use of surnames, and the practice expanded during the reign of Reza Shah (r. 1925–1941). Reza Shah passed a law making it mandatory to have surnames. He himself chose Pahlavi as of his surname, which has its roots in the Sassanid era. Prior to that, a person was often distinguished from others by a combination of prefixes and suffixes attached to his or her name. If it was omitted, that person might be taken for someone else. Since the adoption of surnames, Ahmadi has become the most popular surname in Iran. In many cases individuals were known by the name of the district, city, town, or even the village from which they came by using the locality's name as a suffix, for example: Nuri, Khorasani, Mazandarani, Kordestani, Tehrani, Esfahani, Gilani, Hamedani, and Shirazi. The same rule is followed for the many millions of Iranians who have surnames of regions or cities of the Caucasus region. The latter was forcefully ceded in the course of the 19th century to Imperial Russia through the Treaty of Gulistan (1813) and Treaty of Turkmenchay (1828). Examples of common Iranian surnames in this regard are Daghestani, Qarabaghi, Darbandi, Shirvani, Iravani, Nakhjevani, Lankarani. Among many other secularization and modernization reforms, surnames were required by Reza Shah, following similar contemporary patterns in