 Another previous route that ran through the Persian Gulf via the Tigris and Euphrates rivers was also being threatened by exploitations from the Sassanid Empire, and was being disrupted by the Lakhmids, the Ghassanids, and the Roman–Persian Wars.Mecca's prominence as a trading center also surpassed the cities of Petra and Palmyra.The Sassanids however did not always pose a threat to Mecca, as in 575 CE they protected it from an Yemeni invasion, led by its Christian leader Abraha.