ʿAlī had quitted Medina for Iraq, and the political power centre of Islam left the peninsula, never to return.
In Medina two problems confronted him—the necessity to enforce his role as arbiter and to raise supplies for his moves against Quraysh.
Another agreement made trade with Axum (in what is now Ethiopia) and the African coast secure, as was also the Arabian coastal sea route.
Furthermore, members of the Quraysh house of ʿAbd Manāf concluded pacts with Byzantium, Persia, and rulers of Yemen and Ethiopia, promoting commerce outside Arabia.
They had to pay the tax, but this was not novel because the tribal chiefs had already been taxed to protect the Meccan Islam, however, was destined for a world role.
Under Muhammad’s successors the expansionist urge of the tribes, temporarily united around the nucleus of the two sacred enclaves, coincided with the weakness of Byzantium and Sāsānian Persia.