The Ethiopians could force the Persians out of this profitable trade. To the Arabs Justinian's envoy proposed that they ally with some nomadic tribes of central Arabia to invade the Sasanian domains. Both hopes of the Byzantines were unfulfilled, but the expedition against Iran was not then necessary, since Justinian and the new Sasanian ruler Khusrau had concluded peace. This was also the period of the fall of the Kinda confederacy in northern Arabia and the growth of Lakhmid power.
Some time between 532 and 535 an Ethiopian general Abraha seized power from the Himyarite king and established an independent state in southern Arabia which he gradually enlarged. Abraha declared his independence from Ethiopia, defeated all opponents and received embassies from Byzantium. Abraha, a Christian, was thus pro-Byzantine while some of his enemies appealed to Khusrau for aid against him. Nothing resulted from the different power alliances in Arabia and in 569 or 570 Abraha died. This was "the year of the elephant", the year of the birth of the prophet Muhammad.
In 572 Ma'dikarib, one of the sons of Abraha, fled from his halfbrother, who had become the ruler in southern Arabia, to Khusrau and finally Khusrau moved to support the anti-Byzantine party. The allegiance or sentiments of some of the Monophysite Christians in Arabia changed from a pro-Byzantine position to opposition, since Justin II, who succeeded his uncle in 565, after five or six years of following the policy of reconciliation of his predecessor in vain, turned to a fierce persecution of the Monophysites in the empire. Khusrau sent an army with a small fleet under a commander called Vahriz, together with Saif, son of Abu Murra, to the area near present Aden. The Persians and their allies were victorious, San'a', the capital of southern Arabia, was occupied, and Saif became the new king. This happened between the years 575 and 577.
Southern Arabia thus became and remained a dependency of the Sasanian empire. But the influence of the Himyarite kingdom of southern Arabia on the rest of the peninsula already had declined, preparing the way for the rise of Islam. The Sasanians, however, were interested in controlling the trade of Byzantium to India and the Far East, which they were now able to do thanks to their position in southern Arabia. About 598 a new and larger expedition was sent under command of another Vahriz, since the ruler of the Himyarite kingdom wished to renounce Persian authority. The Persians were successful in battle; the king was killed and southern Arabia became a Sasanian province headed by Vahriz.
To return to Khusrau, the accession of Justin II boded ill for continuing peace between the two empires, for the latter resolved to end Justinian's payments to certain Arab chiefs, who had agreed to refrain from pillaging Byzantine territory in return for subsidies. Justin also sought to obtain possession of Svanetia in the Caucasus, claiming it was part of Lazica, due to Byzantium by the fifty years' peace treaty, although this matter had not been settled in the treaty. In negotiations in Constantinople the emperor showed such intractability in dealing with the Arabs that the Arab chiefs decided to commence raids on Byzantine territory. War between the two empires did not materialize at this time in spite of the embassy from the western Turks in western Turkestan, who came to the Byzantine capital in 568 seeking an alliance between the Turks and Byzantines against their common enemies the Persians and the Avars in the Balkans. Nothing came of this embassy.