Why did Iran of the late 1970s with a thriving economy, wealthy middle class, repressive political system, massive military might, and powerful international allies go through an Islamic revolution, while Egypt of the early 1990s with similar international allies, but poorer economy, impoverished large middle classes, and a more liberal political system did not go beyond developing an Islamist movement?In 1978 the per-capita income in Iran was $2,400, compared to $660 in Egypt in 1988. During the 1970s, some 15 percent of Tehran's population lived in the squatter areas (and about 15 percent in slums), whereas this figure for Cairo in the early 1990s was 50 percent.