Short answers, pulled from the story.
The Balkan Mountains form the northern boundary while the Aegean Sea and Black Sea mark the southern and eastern edges respectively. This area encompasses southeastern Bulgaria, northeastern Greece, and the European part of Turkey.
Romans transformed Thrace into a formal province in 46 AD after ruling it as a tributary state since 31 BC. The Odrysian-Astaean royal family was removed from power before the kingdom passed under Sapaean rule with Bizye as its initial center.
The Odrysian state emerged in the 4th century BC as the first lasting political organization among indigenous Thracians. Mountainous regions maintained warrior traditions while plains tribes were reportedly more peaceable according to historical accounts.
Ottoman Turks conducted their first incursion into Thrace in 1352 and subdued the region completely within two decades. They ruled the territory for five centuries with Edirne serving as the Ottoman capital after the fall of Byzantium in 1453.
Summer 1934 saw up to 10,000 Jews maltreated and forced to leave the region. A large wave of Muslim immigrants called Göçmenler moved from Bulgaria and Romania to East Thrace between 1934 and 1938.