The hypostyle courtyard mosque, common elsewhere in the Islamic world, was in the beginning comparatively rare in the Yemen, although the type had been introduced by the Umayyad caliphs for the Great Mosque of San'a (705-715). In the 10th century this was still the only courtyard mosque in the city. The mosque has a coffered and richly painted wooden ceiling. The monumental portal is first seen in a doorway in the qibla wall of the Great Mosque at San'a (1158). The arch is raised on engaged columns with block capitals on which falcons are depicted and is covered by a ribbed semi-dome. Reliefs to the right and left depict striding lions, a figural theme common in the art of northern Mesopotamia. Arcades, occasionally found in the pre-Islamic Christian architecture of San'a and used in the Great Mosque of San'a in the 8th century, became increasingly common in the period. The minarets date from the 14th century.