When Muhammedanism extended to Persia, it came in touch with the decaying Sassanian empire that from <small>A.D.</small> 226 to 641 had withstood the power of Rome and extended its sway nearly to the gates of India. The remains of its architecture consist chiefly of palaces such as those at =Serbistan=, =Firuzabad=, and =Ctesiphon=. In these, with an inventiveness of their own and on a great scale, the builders combined elements of Assyrian and Roman architecture--square, domed chambers, barrel-vaulted halls, and portals formed of huge arches, elliptical or horseshoe in shape. The direct evidence of this style on the earliest Muhammedan buildings has disappeared owing to the devastation of the Mongol invasion under Genghis Khan; but the Sassanian influence is conjectured from the later architecture which grew up after <small>A.D.</small> 1200. Important examples are to be found in =Bagdad=, =Teheran=, and =Ispahan=. Among the memorials in the last named city is the =Great Mosque=, which has an open court, surrounded by two-storied arcades. Its special features include portal-arches, rising above the highest of the adjoining walls; vaulted aisles, _bulbous-shaped_ domes, and minarets of peculiar elegance. The walls are decorated with enamelled tiles. =India.=--Persian-Muhammedan architecture, probably because of the Sassanian influence, was superior to the Arabian-Muhammedan in constructive elements and represents more fully a developed style. Many of its elements reappear in Indian-Muhammedan architecture, which by the beginning of the fifteenth century was developing a style distinguished alike by the grandeur of the whole and the structural meaning of the details. The finest example of this early period is the =Jama Musjil= (Principal Mosque), at =Ahmedabad=, which Shah Ahmed reconstructed out of a Hindu temple. The Hindu influence is still apparent in the massive detached pillars that buttress the chief entrance. The style reached its full development of structural logic, dignity, and beauty under the Mogul dynasty (1526-1761). By this time the Muhammedan architects had developed a method of dome support, different both from the Byzantine and the Arabic pendentive, which combined corbels, ribs, vaulting surfaces, and corner _squinches_. The last named are arches placed diagonally at the angles to bring the square to an octagonal, which was the favourite form of plan adopted for tombs. Of these the most imposing is the =Tomb of Mahmud= at =Bijapur=.