The Seljuk heir was a man named Seljuk bin Yakak who was employed by Khan Azam of Turkestan. These people were warriors by nature. Allah had to grant this non-Muslim family the happiness of the survival of Islam, the security of the Islamic Empire and the promotion of the religion.
The tribe also migrated with him because he had certain attributes that the tribe considered him as their mentor and guide. He was looking for a religion which is related to human nature. In Bukhara he was introduced to Islam and converted to Islam. The whole tribe became Muslims. That is why its descendants are called Seljuk or Al-Seljuk or Seljuk.
The Seljuk Empire was a Muslim kingdom in the Middle East and Central Asia, founded between the 11th and 14th centuries AD, by the ethnic Oghuz Turks. It is important in Muslim history because it was the last empire to unite the Islamic world after the fall of the Abbasid dynasty.
Its borders stretched from China on one side to the Mediterranean Sea and on the other side with Aden to Khwarazm and Bukhara.