Yahya established his influence in Saada and Najran. He also tried to capture Sana'a from the Yufirids in 901 CE but failed miserably. In 904, the Isma'ilis under Ibn Hawshab and Ali ibn al-Fadl al-Jayshani invaded Sana'a. The Yufirid emir As'ad ibn Ibrahim retreated to Al-Jawf, and between 904 and 913, Sana'a was conquered no less than 20 times by Isma'ilis and Yufirids. As'ad ibn Ibrahim regained Sana'a in 915. Yemen was in turmoil as Sana'a became a battlefield for the three dynasties, as well as independent tribes.