Before The Komnenoi
In the decades before the Komnenoi, the Byzantine Empire had been on a steady decline, aided by weak emperors who squandered the gold fortunes of the Empire and allowed the military system to fall into neglect. The empire's holdings in Southern Italy were finally lost to the Normans who, under Robert Guiscard and his son Bohemond of Taranto, quickly turned to the weakly held Balkan provinces of Byzantium that were ripe for plunder. Meanwhile, on the Anatolian front, the Byzantine frontier defenses fell into decay as successive emperors disbanded the large standing armies of previous eras in order to save money. Instead of a professional army, they relied on mercenaries and aging conscripts to defend the tenuous frontier. The Emperor Romanos Diogenes tried to re-assert Byzantine dominance in Anatolia, but he was surprisingly defeated and captured at the Battle of Manzikert in 1071 by the Seljuk leader Alp Arslan, a seminal moment in Byzantine history. After his capture the empire descended into civil war as many grappled for the Imperial purple in Constantinople. During this time, much of Anatolia was overrun by the Seljuk Turks and the military of the empire completely fell apart as defensive positions were abandoned and territory was quickly lost to the advancing Turks.
Read more about this topic: Komnenian Restoration