At least three asynchronous waves can be differentiated in the visible phenomena of archaeological materials from Estonia, the beginning of which lies in the forest zone of East Europe (mostly the Volga-Oka region), having spread to the Baltic Sea and which can be correlated with the arrival of groups of people speaking West Uralic. It is conceivable, however, that people migrated from the east constantly, also between peaks of migration.
The arrival of the so-called vanguard or pioneers is indicated by the first settlements in which the findings include early Tapiola style pottery. Based on existing datings, this wave began in the last centuries of the 2nd millennium BC.
Larger quantities of people arrived when fortified settlements began to be built. This form of habitation reached the River Daugava around the turn of the 2nd and 1st millennium BC and to Estonia, southwestern Finland and eastern Central Sweden a century or two later. The mentioned settlements were situated mostly along waterways, creating an essential network of supporting locations for mobility. The type of settlement was the same for both the Finnic and the Baltic (i.e. Proto-Baltic) tribes.
The third essential wave arrived at the end of the Bronze Age and brought with it the early tarand graves. That at least a part of those buried in the tarand graves came from elsewhere, apparently from the east, is confirmed by both the values for strontium isotopes as well as data from ancient DNA.
All the immigrants followed the route from the River Volga to the Upper Dniepr, and thence to Upper Daugava and along the River Daugava to the shores of the Baltic Sea, that is, along the connecting ways of the southwestern route.
