 A number of distinct architectural traditions arose for expressing these social elements.The Islamic tradition was slow in starting; the "hadith" "condemn the building of tombs, and Muhammad himself set the example of requesting burial in an unmarked grave in one of the chambers of his house" in Medina, though by at least the 12th century, buildings of the vast Al-Masjid an-Nabawi complex already marked the site.The earliest identified Muslim monumental tomb, in Samarra in Iraq, only dates from 862, and was commissioned by the Byzantine princess whose son was buried there.