The Byzantine Empire or Byzantium is the term conventionally used since the 19th century to describe the Greek-speaking Roman Empire of the Middle Ages, centered around its capital of Constantinople.

As the direct continuation of the Roman Empire, Byzantium survives the fall of the Western Roman Empire during Late Antiquity, and continues to function until its conquest by the Ottoman Empire in 1453.

During this time, many different imperial dynasties rule over the empire; in the context of Byzantine history, the period c.1185 – c.1204 CE is under the Angeloi dynasty.The Angeloi rise to the throne following the deposition of Andronikos I Komnenos, the last male-line Komnenos to rise to the throne.

The Angeloi are female-line descendants of the previous dynasty.

While in power, the Angeloi fail to stop the invasions of the Turks by the Sultanate of Rum, the successful uprising and resurrection of the Bulgarian Empire, and the loss of the Dalmatian coast and much of the Balkan areas won by Manuel to the Kingdom of Hungary.Ruled with total incompetence, Byzantium permanently loses her financial capability and military power; her previous policies of openness with Western Europe guarantee Western invasions, which end the Byzantine Empire centered at Constantinople in 1204 when soldiers of the Fourth Crusade overthrow the last Angeloi Emperor, Alexios V Doukas.The Fourth Crusade is seen by historians today as the death knell of the Byzantine Empire.

It is therefore no exaggeration to suggest that the Angeloi led Byzantium to her ultimate demise.

Every emperor of the Angeloi dynasty was either deposed or killed, with the exception of Isaac Angelus who was restored for a brief time after his desposition.