The first Shah rose to power in 1925. The second Shah took over after the death of the first Shah. During the second Shah's reign, a revolution took place and the Shah was forced to step down. He used SAVAK, his secret police to ensure the obedience of the people. However, after restrictions were placed on his military, people began to revolt. During his rule, people were scared away by the army and any act of rebellion could get the person arrested, tortured, and possibly killed by SAVAK.
Below is a map of Iran in relation to the rest of the Eastern hemisphere.