Many Poles were also exiled to Siberia (see Sybiraks).
While the comparably flat Western Siberia was at least fairly well served by the gigantic Ob-Irtysh-Tobol-Chulym river system, the mighty rivers of Eastern Siberia -- Yenisei, Upper Angara River (Angara River below Bratsk was not easily navigable because of the rapids), Lena-were mostly navigable only in the north-south direction.