In 395, after the division of the Roman Empire into East and West, the Illyrian lands of Moesia (Serbia) Dardania (Kosovo) and Epirus (Albania) fell to the east. The east, the Byzantine Empire, called their political units themes, large states led by a deputy to the emperor, with several provences such as Vlora, and Lezha, in central Albania or Praevlitania, in the northern Albania, or Moesia in modern Serbia; each were ruled by nobles. On a larger level, there were four prateorian prefectures, which were divided into dioceses.
Emperor Justinian, 527 to 565, built many fortifications to defend the Empire. Eventually, the invaders would come, and great as defence was, the wave could not be stopped. Though he built 26 forts in Illyria, his home, IIlyria itself would be most affected by invasion. The first invaders came from central Europe from the Germanic peoples. The Goths, and the Iranian Sarmatians, swept through Balkan regions such as Thrace (Bulgaria), Macedonia, Dardania, Epirus. etc. Though they wrought great violence and suffering, they left no trace on the people and place. The Huns came from the east in 441 followed by the Avars, to further ruin Dardania and Macedonia. Ostragoths from the north would follow in 459.
These periodic invasions however would only increase in the 500s and 600s. The new wave would begin from the East where the Bulgars, a Turkic people, would defeat an Illyrian army in Thrace and settle the land. Constant wars would weaken the Byzantine army and its capacity to defend the empire, which only led to further invasion, and finally permanent settlement. The waves of settlers would come from the north and east, from the Slavic peoples; these people, who were numerous and particularly ruthless, would ravage the empire, killing, expelling or assimilating the natives. So bold and unstoppable were these invaders that they attempted to capture Constantinople itself; in this ambitious campaign, however, they were defeated. But they would forever change the ethnic composition of the Balkans. Today their descendants live in the modern countries of Slovenia, Bosnia and Herzegovina, Montenegro, Serbia, Macedonia and Bulgaria.
Illyria would loose Moesia to the Serbs and all territory north of modern Albania; though today there exists an Albanian minority in neighboring Slavic countries, like Monte Negro, as well as Macedonia, which is 25 percent Albanian. Ancient Dardania, modern Kosovo, would have centuries of conflict with the Serbs, until it gained independence as its own country in 1999.
From the east came further invasion into central Albania, this time from the Bulgars, who themselves now had been overrun by the more numerous Slavs. The Bulgarian Slavs were to build a kingdom in 851 whose zenith would be in the 10th century, and whose reach would extend through Macedonia, northern Greece, and central Albania. Though it would last for close to two centuries, until 1018, it would have no permanent impact on Albania, other than some Slavic place names or words.
From the west, Albania and the Balkans would have yet more invasion, this time from the Normans, an adventurous Viking people, who are most known for conquering England in the year 1066. In 1081, the Normans invaded Vlora and proceeded to Durres without much resistance. Meanwhile Emperor Alexius called on Venice for support. On the sea, the Normans would loose to the Venetian force, but not on land; all of Albania and Thessaly (Northern Greece) would be occupied until 1085, when Alexius raised another army and routed the invaders. Yet the Normans would return once more in 1107, this time without success. So weak was their campaign in Durres that their leader Bohemond instead of conquering, joined the Empire as a governor in Asia Minor.
Zavalani, Tajar. (1903-1966) Histori e Shqipnis, 1957, Tirana. History of Albania. London, 1963. Reprinted, 2015 Robert Elsie and Bejtullah Destani, editors.
Elsie, Robert. (1950-2017) Albania in a Nutshell, 2015.
Painting by Viktor Vasnetsov 1881