Seljuk was the "bey" (chieftain) of a branch of Oghuz Turks known as the Kýnýk Seljuqs. He founded the Seljuq dynasty around year 1000. Tradition says Seljuk had four sons: Mikail, Junus, Musa and Arslan. Seljuk's grandson Toghrül, son of Mikail conquered Persia (Iran) in the mid-11th century. According to some sources, Seljuk began his career as an officer in the Khazar army. Wikipedia
The definitive Wikipedia entry for Seljuk. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Seljuk