thracians - Extinction of the ethnicity and language
See also Dacian language, Thracian language.
The ancient languages of these people had already gone extinct and their cultural influence was highly reduced due to the repeated barbaric invasions of the Balkans by Celts, Huns, Goths, and Sarmatians, accompanied by persistent hellenization, romanisation and later slavicisation. The ethnic contribution of the Thracian and Daco-Getic population, who had lived on the territory of modern Bulgaria and Romania has been long debated among the scientists during the 20th century. Some recent genetic studies suggest that these peoples have indeed made a significant contribution to the genes of these nations.http://www.legmed.ro/files/revista/2004-4/02-Cardos-%20MtDNA.pdf
After they were subjugated by the Macedonian king Alexander the Great and consecutively by the Roman empire, most of the Thracians eventually became Hellenised (in the province of Thrace) or Romanised (in Moesia, Dacia, etc.). The Romanised tribes of Dacia later became the ethnic substratum of the Vlach people (that first appeared in historical documents in the 10th century) who evolved into modern Romanians.
In the 6th century some Thracian tribes south of the Danube river made contacts with the invading Slavs and were later Slavicised. Thus they became one of the main ethnic elements in the consolidation of the Bulgarian nation in 8-9th century. Linguistic evidence about this is the presence of Thracian and direct Latin loanwords in Old Bulgarian and modern Bulgarian language.
Some scholars have proposed that present-day Albanians may be descendants of Thracian tribes who maintained their language. However this is highly controversial as the official Albanian historiography relates modern Albanians with the ancient Illyrian people. Bulgarian historians also consider it possible for the Vlach and Karakachani people of Bulgaria to be descendants respectively of Romanised and Hellenised Thracian tribes.