How did the Seljuk Turks gradually replace the Abbasid's?

The Seljuk Turks gradually replaced the Abbasids by capitalizing on the weakening political and military power of the Abbasid Caliphate during the 10th and 11th centuries. As the Abbasids struggled with internal strife and external threats, the Seljuks, originally a nomadic tribe, began to establish control over Persia and the eastern territories of the Caliphate. They effectively became the military and administrative leaders, culminating in the capture of Baghdad in 1055, where they positioned themselves as protectors of the Caliphate while diminishing its authority. This shift marked the transition of power from the Abbasids to the Seljuks, who would dominate the region for several centuries.