What condition made the Byzantines vulnerable to attack by Muslim Turks?

The condition that made the Byzantines vulnerable to attack by Muslim Turks can be attributed to a combination of several factors. One significant factor was the prolonged exhaustion caused by centuries of warfare, particularly with the Sassanian Empire and the Arab Caliphates. Another contributing factor was a significant decline in population and economic resources.

To get a better understanding of how these factors made the Byzantines vulnerable, one can delve into the study of Byzantine history and analyze the various sources. This can involve reading books and articles on the topic, consulting scholarly journals, or attending lectures from experts in the field. By gathering multiple perspectives and interpretations of the historical events, one can form a comprehensive understanding of the Byzantine Empire's vulnerabilities.