In 1453, the Byzantine Empire (the Eastern Roman Empire) was defeated by the Ottoman Empire and its territory in Asia Minor including its capital Constantinople became part of the Ottoman Empire.
The citizens of the Byzantine Empire (in Turkish Rum and in English Romans) became citizens of the Ottoman Empire and continued to live in their homelands in peace for centuries.
At the end of the WWI, the Ottoman Empire ceased to exist, and the newly formed Republic of Turkey was created.
Gradually, the Romans started leaving their homelands and became refugees in Greece and in other countries and continents mainly because, the newly formed Turkish government at the time, enforced new laws where the Romans were not given Turkish Nationality and they were not allowed to sell, donate or transfer the movable or immovable assets they owned in Constantinople and in Asia Minor.
Consequently, their assets remained unattended for a long time and were eventually assumed by Third Parties.
Currently the legal environment in the Republic of Turkey is in favour of the living heirs/inheritors to recover their ancestors’ assets.