Proto-Finnic began diverging already during the second half of the I millennium BC. It was probably then that many regional dialects developed, because the territory inhabited by the Finnic people was fairly large and sparsely populated. However, we know only of two dialects that developed at that time: one was the dialect from which South Estonian developed, the other what we call Late Proto-Finnic. In the course of the so-called second coming of Finnic (cf. 1.2.3) the Late Proto-Finnic of the North Estonians levelled the previously formed dialectal differences wherever its reach extended.
Late Proto-Finnic remained somewhat uniform until the Viking Age, because the most recent common feature of the Finnic languages – early Slavic loanwords – can not be dated earlier. Since the Slavic loanwords did not spread evenly to all the Finnic languages, the divergence of the proto-language had by that time already begun. Based on archaeological materials, especially pottery, the development of four larger groups becomes visible from the 7th-8th century onwards: North Estonia (Iru type pottery), South Estonia (Rõuge), the lower course of Daugava river (Daugmale) and Southwest Finland (Vanhalinna). Temporally and geographically these cultural groups match the development of the North Estonian, South Estonian, Livonian and West Finnish languages. A fifth group was located at the eastern side of Estonia and Pskov region, where the deceased were buried in sand barrows. The larger cultural distinguishability of this group does not permit connecting them directly to Finnic peoples, but to some other West Uralic people. Also in Karelia, the culture originating from Southwest Finland began to spread from the 7th-8th century, although it developed truly idiosyncratic in the 12th-14th centuries. Also Izhorian and Veps developed out of Karelian influence, whereas the Votic language divereged from North Estonian.
