 As Russian settlements continued to spread through the Yenisei, Tobol and Irtysh watersheds in the course of the 18th century, so did the development of the Omsk and the surrounding region.In 1753 a customs post was established to tax goods brought into the city by the ever-increasing trade with Kazakh tribesmen.In 1764, when he Siberian provinces of Russia were organized into two governorates with centers in Irkutsk and Tobolsk, the city of Tara and the fortress of Omsk were assigned to the latter.