The History of the Decline and Fall of the Roman Empire, by Edward Gibbon

Chapter LVII: The Turks

The Turks Of The House Of Seljuk.—Their Revolt Against Mahmud Conqueror Of Hindostan.—Togrul Subdues Persia, And Protects The Caliphs.—Defeat And Captivity Of The Emperor Romanus Diogenes By Alp Arslan.—Power And Magnificence Of Malek Shah.—Conquest Of Asia Minor And Syria.—State And Oppression Of Jerusalem.—Pilgrimages To The Holy Sepulchre.