The Squinch Before and Beside Islam

The squinch predates Islamic architecture by centuries and was never exclusive to it. Sasanian Persian fire temples used corbelled squinches to carry domes over square sanctuaries well before the seventh century, and Byzantine church architecture developed pendentives, a related but geometrically distinct solution using concave triangular sections rather than corner arches, to solve the same square-to-dome problem for buildings such as the sixth century Hagia Sophia. Early Islamic builders, working across formerly Sasanian and Byzantine territory, inherited both devices and used them somewhat interchangeably at first, with squinches more common in the eastern Islamic lands closer to the Persian tradition and pendentives more common where Byzantine building practice was strongest.

Over time squinches became the dominant device in Iranian, Central Asian and much of the wider Islamic world, developing from plain corbelled arches into increasingly elaborate multi-tiered and eventually muqarnas forms, while pendentives remained the standard solution in Byzantine and later Ottoman domed architecture, itself heavily influenced by Hagia Sophia. The two devices therefore sit on either side of a real historical boundary, Persian and Byzantine respectively, that Islamic building inherited whole rather than invented, and a single tradition's later choice between them often signals which of the two antecedent building cultures most shaped its regional school.