How did the four-iwan mosque plan become important in Iranian architecture?

The four-iwan mosque plan, which features a central rectangular courtyard adjoined on each side by an iwan—a vaulted hall opening into a tall arch—first appeared in the Iranian city of Esfahan.

While early Islamic architecture was dominated by the hypostyle tradition, Iranian architecture often utilized distinct, localized plans. The four-iwan design emerged as a significant development during the Seljuq dynasty, which ruled parts of Iran in the 11th century. The Great Mosque of Isfahan serves as a primary example of this evolution; the structure was rebuilt in the early 12th century around this four-iwan configuration.12

This design eventually became the standard for Iranian mosques and exerted a notable influence on the architecture of neighboring regions, including the construction of madrasahs in the Fertile Crescent.3