(al-Tughrai). Berkyaruq then led an expedition as far east as Tirmidh, where he confirmed the Qarakhanids Sulayman-tegin and Mahmud-tegin as the vassal rulers of Transoxiana. He also appointed Qutb al-Din Muhammad as the new governor of the Central Asian region of Khwarazm, thus marking the start of the Khwarazmian dynasty. He spent seven months in the city of Balkh, and then returned to the west. However, after leaving his eastern possessions, the area was plunged into a series of revolts, including one by the Seljuk prince Dawlatshah. The name of Berkyaruq started to get excluded from the coins struck at Nishapur, which testifies to the slow disintegration of his rule in Khurasan. Preoccupied by continuous internal issues, Berkyaruq was unavailable to respond to the advent of the First Crusade in Syria in 1097. The crusaders besieged Antioch and sacked Ma'arrat al-Nu'man. Furthermore, Berkyaruq had little reason to help the Seljuks of Syria, who fought amongst themselves, dividing the country. The northern part was ruled by Fakhr al-Mulk Radwan, and the southern part by Shams al-Muluk Duqaq. When the Crusaders entered Syria, Ridwan shifted his allegiance from Berkyaruq to the Fatimid Caliphate. Conflict with Muhammad I Tapar The most difficult challenge that Berkyaruq faced was the rebellion of his half-brother Muhammad in 1098 or 1099. The rebellion had been encouraged by Nizam al-Mulk's son Mu'ayyid al-Mulk, who had formerly served Berkyaruq and played a key-role in the defeat of Tutush. After his dismissal by Berkyaruq, he entered into the service of Muhammad, who appointed him as his vizier. Mu'ayyid al-Mulk made use of his newfound position to exact vengeance on his rivals, which was made easier because Muhammad had yet to reach adulthood (approximately 17 years old at the time). The Nizamiyya and the prominent families of Isfahan also joined Muhammad, stopping Berkyaruq from entering the city. The rebellion was launched from Muhammad's base at the city of Ganja in Arran, which had been given to him as an iqta' (land grant) by Berkyaruq back in 1093. Muhammad's capture of Ray exposed the vulnerability of Berkyaruq's realm. Sa'd al-Dawla Gawhara'in, the shihna (military administrator) of Baghdad, soon joined Muhammad, which implies that the city was also added to his domain. Nevertheless, the five-year war continued to be indecisive, with Baghdad repeatedly changing hands. Even with the support of Sanjar (who despised Berkyaruq), Muhammad was unable to defeat his rival. Berkyaruq's authority