The Slavs had fully settled in the area by the middle of the 6th century.
This was done peacefully as there are no records for their attacks.
 With the establishment of Bulgaria in 681, Philippoupolis, the name of the city then, became an important border fortress of the Byzantine Empire.
It was captured by Khan Krum in 812, but the region was fully incorporated into the Bulgarian Empire in 834 during the reign of Khan Malamir.
It was reconquered by the Byzantine Empire in 855–856 for a short time until it was returned to Boris I of Bulgaria.
From Philippopolis, the influence of dualistic doctrines spread to Bulgaria forming the basis of the Bogomil heresy.
The city remained in Bulgarian hands until 970.
However, the city is described at the time of Constantine VII in the 10th century as being within the Byzantine province (theme of Macedonia).
Philippopolis was captured by the Byzantines in 969, shortly before it was sacked by the ruler of Rus' Sviatoslav I of Kiev who impaled 20,000 citizens.
Before and after the Rus' massacre, the city was settled by Paulician heretics transported from Syria and Armenia to serve as military settlers on the European frontier with Bulgaria.
Aime de Varennes in 1180 encountered the singing of Byzantine songs in the city that recounted the deeds of Alexander the Great and his predecessors over 1300 years before.

Byzantine rule was interrupted by the Third crusade (1189–1192) when the army of the Holy Roman emperor Frederick Barbarossa conquered Philippopolis.
Ivanko was appointed as the governor of the Byzantine Theme of Philippopolis in 1196, but between 1198 and 1200 separated it from Byzantium in a union with Bulgaria.
The Latin Empire conquered Philippoupolis in 1204, and there were two short interregnum periods as the city was twice occupied by Kaloyan of Bulgaria before his death in 1207.
In 1208, Kaloyan's successor Boril was defeated by the Latins in the Battle of Philippopolis.
Under Latin rule, Philippopolis was the capital of the Duchy of Philippopolis, which was governed by Renier de Trit and later on by Gerard de Strem.
The city was possibly at times a vassal of Bulgaria or Venice.
Ivan Asen II conquered the duchy finally in 1230 but the city had possibly been conquered earlier.
Afterwards, Plovdiv was conquered by Byzantium.
According to some information, by 1300 Plovdiv was a possession of Theodore Svetoslav of Bulgaria.
It was conquered from Byzantium by George Terter II of Bulgaria in 1322.
Andronikos III Palaiologos unsuccessfully besieged the city, but a treaty restored Byzantine rule once again in 1323.
In 1344 the city and eight other cities were surrendered to Bulgaria by the regency for John V Palaiologos as the price for Ivan Alexander of Bulgaria's support in the Byzantine civil war of 1341–47.
The Slavs had fully settled in the area by the middle of the 6th century. This was done peacefully as there are no records for their attacks.  With the establishment of Bulgaria in 681, Philippoupolis, the name of the city then, became an important border fortress of the Byzantine Empire. It was captured by Khan Krum in 812, but the region was fully incorporated into the Bulgarian Empire in 834 during the reign of Khan Malamir. It was reconquered by the Byzantine Empire in 855–856 for a short time until it was returned to Boris I of Bulgaria. From Philippopolis, the influence of dualistic doctrines spread to Bulgaria forming the basis of the Bogomil heresy. The city remained in Bulgarian hands until 970. However, the city is described at the time of Constantine VII in the 10th century as being within the Byzantine province (theme of Macedonia). Philippopolis was captured by the Byzantines in 969, shortly before it was sacked by the ruler of Rus' Sviatoslav I of Kiev who impaled 20,000 citizens. Before and after the Rus' massacre, the city was settled by Paulician heretics transported from Syria and Armenia to serve as military settlers on the European frontier with Bulgaria. Aime de Varennes in 1180 encountered the singing of Byzantine songs in the city that recounted the deeds of Alexander the Great and his predecessors over 1300 years before.
Byzantine rule was interrupted by the Third crusade (1189–1192) when the army of the Holy Roman emperor Frederick Barbarossa conquered Philippopolis. Ivanko was appointed as the governor of the Byzantine Theme of Philippopolis in 1196, but between 1198 and 1200 separated it from Byzantium in a union with Bulgaria. The Latin Empire conquered Philippoupolis in 1204, and there were two short interregnum periods as the city was twice occupied by Kaloyan of Bulgaria before his death in 1207. In 1208, Kaloyan's successor Boril was defeated by the Latins in the Battle of Philippopolis. Under Latin rule, Philippopolis was the capital of the Duchy of Philippopolis, which was governed by Renier de Trit and later on by Gerard de Strem. The city was possibly at times a vassal of Bulgaria or Venice. Ivan Asen II conquered the duchy finally in 1230 but the city had possibly been conquered earlier. Afterwards, Plovdiv was conquered by Byzantium. According to some information, by 1300 Plovdiv was a possession of Theodore Svetoslav of Bulgaria. It was conquered from Byzantium by George Terter II of Bulgaria in 1322. Andronikos III Palaiologos unsuccessfully besieged the city, but a treaty restored Byzantine rule once again in 1323. In 1344 the city and eight other cities were surrendered to Bulgaria by the regency for John V Palaiologos as the price for Ivan Alexander of Bulgaria's support in the Byzantine civil war of 1341–47.
Plovdiv