Modern banknotes often carry the portrait of the country's head of state. In times of sudden political change, these notes may become undesirable to the new authorities.This occurred in Iran during the revolution of 1978-79. Mohammad Reza Shah Pahlavi (1919-1980), the established ruler, was overthrown by the Islamic forces of Ayatollah Ruhollah Khomeini (1901-89) and forced to flee the country. As a temporary measure, the Shah's portrait on the banknotes was obliterated by a heavy black arabesque pattern. Even the watermark, which also showed the Shah's head, was overprinted with the name of the new Islamic republic.Later, new note designs were issued featuring the Ayatollah and revolutionary supporters.