After the crusaders of the Fourth Crusade captured Constantinople in 1204 and shattered the Byzantine view of unbroken continuity from Rome to Constantinople, new alternative sources were required for the legitimacy of the Byzantines as Romans.
The Byzantine elite thus began to increasingly detach their self-identity from the Roman Empire as a unit and look to Greek cultural heritage and Orthodox Christianity as the markers of what Romans were, and connected the contemporary Romans to the ancient Greeks as the precursors who had once ruled the current homeland of the Romans.
Ethnic Romanness became increasingly identified as someone who was ethno-culturally Hellenic, an idea which was taken a step further by Emperors John III and Theodore II (who ruled at Nicaea while the Crusaders and their descendants occupied Constantinople), who stated that the present Rhomaioi were Hellenes, descendants of the Ancient Greeks.

This is not to say that the Byzantines stopped identifying as Romans.
The Byzantine view changed from Constantine the Great bestowing the empire to Constantinople to Constantine the Great bestowing the empire to the Hellenes and as such a Roman and a Greek was the same thing.
This in no way invalidated them as Romans; though the Nicaean emperors explicitly referred to their lands and subjects as Hellenic, they also identified themselves as the only true Roman emperors. "
Greek" and "Roman" were not contrasting or distinct identities, but building blocks of the same identity as Rhomaioi.
This double-identity lasted beyond the 1261 reconquest of the city under Emperor Michael VIII Palaiologos and remained the main view on the issue by the time of the last few Byzantine emperors.
In the text Comparison of the Old and the New Rome by Manuel Chrysoloras, addressed to Emperor Manuel II Palaiologos, Rome is presented as the mother of the daughter Constantinople, a city founded by the two most wise and powerful peoples in the world, the Romans and the Hellenes, who came together to create a city destined to rule the entire world.
After the crusaders of the Fourth Crusade captured Constantinople in 1204 and shattered the Byzantine view of unbroken continuity from Rome to Constantinople, new alternative sources were required for the legitimacy of the Byzantines as Romans. The Byzantine elite thus began to increasingly detach their self-identity from the Roman Empire as a unit and look to Greek cultural heritage and Orthodox Christianity as the markers of what Romans were, and connected the contemporary Romans to the ancient Greeks as the precursors who had once ruled the current homeland of the Romans. Ethnic Romanness became increasingly identified as someone who was ethno-culturally Hellenic, an idea which was taken a step further by Emperors John III and Theodore II (who ruled at Nicaea while the Crusaders and their descendants occupied Constantinople), who stated that the present Rhomaioi were Hellenes, descendants of the Ancient Greeks.
This is not to say that the Byzantines stopped identifying as Romans. The Byzantine view changed from Constantine the Great bestowing the empire to Constantinople to Constantine the Great bestowing the empire to the Hellenes and as such a Roman and a Greek was the same thing. This in no way invalidated them as Romans; though the Nicaean emperors explicitly referred to their lands and subjects as Hellenic, they also identified themselves as the only true Roman emperors. "Greek" and "Roman" were not contrasting or distinct identities, but building blocks of the same identity as Rhomaioi. This double-identity lasted beyond the 1261 reconquest of the city under Emperor Michael VIII Palaiologos and remained the main view on the issue by the time of the last few Byzantine emperors. In the text Comparison of the Old and the New Rome by Manuel Chrysoloras, addressed to Emperor Manuel II Palaiologos, Rome is presented as the mother of the daughter Constantinople, a city founded by the two most wise and powerful peoples in the world, the Romans and the Hellenes, who came together to create a city destined to rule the entire world.
Roman people