ABSTRACT
The most striking geographical factors are the desert separating and isolating Umân from the rest of the peninsula, the mountain range running through the country and the coastline facing toward the Arabian Sea and Indian Ocean, opening umân to a maritime world. The northwestern portion of the range is called al-Ḩajar al-gharbî and the southeastern portion, al-Ḩajar al-sharqî. The Sâsânids took a strong interest in the Mazûn province, further developed the qanât system, and made Şuḩâr the maritime capital with al-Rastâq the inland capital under an Arab chief of the Julandâ. Arab immigration continued, from both the north and south. The relationship among these groups is not clear but has been oversimplified as Adnânî-Qaḩânî, reflecting an alleged fundamental tribal split among all Arabians. The immigration has also been associated with tribal movements after the quasi-historical breaking of the Marib dam in South Arabia in the fifth century AD.
