According to traditional historians, the Ghassanids were part of the al-Azd tribe, and they emigrated from South Arabia, modern day Yemen. They traveled across the Arabian Peninsula and eventually settled in the Roman limes. The tradition of Ghassanid migration finds support in the Geography of Claudius Ptolemy, which locates a tribe called the Kassanitai south of the Kinaidokolpitai and the river Baitios (probably the wādī Baysh). These are probably the people called Casani in Pliny the Elder, Gasandoi in Diodorus Siculus and Kasandreis in Photios (relying on older sources).