Persian architecture likely inherited an architectural tradition of dome-building dating back to the earliest Mesopotamian domes. Due to the scarcity of wood in many areas of the Iranian plateau and Greater Iran, domes were an important part of vernacular architecture throughout Persian history. The Persian invention of the squinch, a series of concentric arches forming a half-cone over the corner of a room, enabled the transition from the walls of a square chamber to an octagonal base for a dome in a way reliable enough for large constructions and domes moved to the forefront of Persian architecture as a result. Pre-Islamic domes in Persia are commonly semi-elliptical, with pointed domes and those with conical outer shells being the majority of the domes in the Islamic periods.