Toponymy between Sofia and Plovdiv in the 10th and 11th centuries indicates that (Proto-)Albanian populations had migrated from their native lands to the eastern Balkans before the era of Leka.
Their geographical proximity is explained by their common migration to Bulgaria in the early Middle Ages as shepherd populations from a wide area from northern Albania to the central Balkans.
[3] Some of the earliest Albanian settlers in modern Bulgaria were the Roman Catholic ore miners in Kopilovtsi, Montana Province, a village in the vicinity of the larger mining centre Chiprovtsi.
In 1626, the Archbishop of Bar Pjetër Mazreku claims that part of the Bulgarian Catholics are Albanians (Albanesi), Saxons and Paulicians.
[6] Other places in northern Bulgaria where an Albanian presence has been strongly suggested are Chervena Voda near Rousse, Poroishte near Razgrad, Dobrina near Provadia and Devnya near Varna.
[11] Most notably, the text of the Albanian national anthem, Aleksander Stavre Drenova's Hymn to the Flag, was first published in Sofia by the Freedom of Albania newspaper.