Tughril soon decides to put an end to the Buyid state in Iraq.

Under cover of intended pilgrimage to Mecca, the Seljuq ruler enters Iraq with a heavy force, and, assuring the Caliph of pacific views and subservience to his authority, begs permission to visit the capital.

He makes it known that after he returns, he will make war with the Fatimids.

The caliph, who had initially preferred the weak Buyids over the strong Seljuqs despite the latter's Sunni orthodoxy, declares that Tughril’s name should be recited before that of al-Malik al-Rahim in the Friday sermons.

The amir thereupon becomes a vassal of the Seljuqs.

A few days after, on December 17, 1055, Tughril himself—having sworn to be true not only to the Caliph, but also to the Buuid amir, Abu Nasr al-Malik al-Rahim, makes his entry into the capital, where he is well received both by chiefs and people.

Barely a week passes, however, before the citizens of Baghdad begin to complain to the amir about looting committed by the Seljuq troops, asking him to expel them out of the city.

Tughril then summons him to his camp to negotiate over the issue.

When he arrives, he is accused of acts of retribution against the Seljuq troops, and is arrested over the caliph's protests.

The last Buyid ruler of Iraq, Al-Malik al-Rahim will die a prisoner in Ray in 1058 or 1059.