ok the following is from Britannica

hope it may give you an idea

also spelled  Seljuk  ruling military family of the Oguz (Ghuzz) Turkmen tribes that invaded southwestern Asia in the 11th century and eventually founded an empire that included Mesopotamia, Syria, Palestine, and most of Iran. Their advance marked the beginning of Turkish power in the Middle East.

During the 10th-century migrations of the Turkish peoples from Central Asia and southeast Russia, …

Oguzoglu, hello.

The founder hero of Seljuks is son of a certain Duqaq (Subasi) named Timuryalik from the tribe of Kinik. He immigrated to Syr i Derya region just before 985. Some says he was Nestorian, because his sons had Biblical names: Musa, Mikail, Israil. Grousset claims, it is highly likely that Samanids forced Seljuk Begh to convert to Islam because they immigrated on the borders of Samanid Transoxiana. In his period Karahanlis were attacking Samanids. I can not understand Grousset, sorry about this, what he says one part, does not hold in another part. He says Karahanlis dominate the Samanids, and Satuk Bugra Han who died in 955 prefered islam while beating muslim samanids. The most probable thing is Karahanlis as the father of Turks in those days forces Seljuks to convert because they came to their lands. Anyway who would immigrate to the trouble lands. And it is highly possible Karahanlis called them to come there because they were tyhe auxiliary force of Karahanlis.

Seljuks, in the beginning, were under the Karahanli rule. Later Arslan, muslim name Israil, son of Seljuk declares him as Yabghu and acted as an Auxiallry of Karahanids against the Ghaznawids (anyway they are slave converts, I do not like being a slave, a Turk should commit suicide rather than putting in a cage).

Mahmut the Ghaznavid took him as a prisoner.

Seljuk Begs grandson Tughrul and Cagri asked for Khurasan to be given to Seljuk Yabghus. Mesud of Ghazna refused. Seljuks seized Nishapur in 1038. Near Merv in Dandanakan, Seljuks defeated Ghaznavids abd Kurasan became Turkish land (Small part of Khurasan was invaded by Gokturks however when the empire collapsed, we had to go back to Mongolia).

Caghri Beg, big brother of Tughrul invaded Harzem in 1042-43.

Abbasid Caliph requested the help of Seljuks in 1055 against the Buwayhids.

THey invaded Baghdad the same year and kick the Buwayhids away from Baghdad. Since that day till 1917, arabs were under Turkish rule. 

His cousin Kutalmis to Azerbaycan region. The son of Kutalmis desired to capture Rome, while Romanus IV Diogenes attacked Seljuks. Alparslan, the emperor on the other hand wanted to kick Fatimids of Egypt and become the supreme power of Islam. You know the rest of the story, battle of Manzikert occured in 1071, after the victory, Alparslan insisted on resisting the invasion of Roman lands. Just in a couple of years, Suleiman, son of Kutalmis convinced Alparslan and started the invasion of Anatolia.

Seljuks were cool. arabs should thank to Satuk Bughra Han. He himself converted to islam, he liked the religion, while defeating the Samanids, convinced other Turks to become muslim like Seljuks. Others would not do that. THat is where god shows the power, islamic world needed the powerful Turkic military skills. Seljuks are important because they defended the islamic world against the Crusades. If they were not muslims, arabs would be forcibly converted to Christianity. Anyway, their victory in Manzikert caused the crusades.

But arabs hate Slejuks and Toghril Begh. That is why they lost always in the previous millenium. They spit on the hand which survives them.