Jireček Line

The Jireček Line is a conceptual boundary through the ancient Balkans that divides the influence of the Latin (in the north) and Greek (in the south) languages in the Roman Empire from antiquity until the 4th century.

[1] A possible rough outline of it goes from near Lissus (near Lezhë and Laç in modern Albania) to Serdica (now Sofia, in Bulgaria) and then follows the Balkan Mountains to Odessus (Varna) on the Black Sea or continuing along the coastline northwards to the Danube Delta.

It was used originally by Czech historian Konstantin Jireček in 1911 in a history of the Slavic people.

Already during antiquity there were significant exceptions: there were Hellenized groups north of the line (e.g. the Greek colonies along the western coastline of the Black Sea) and Latinized groups may have lived south of the line.

He also states that during the pre-Byzantine Roman period, "even in Greek areas... Latin was the dominant language in inscriptions recording public works, on milestones, and in the army".