The relatively low middle Ural Mountains at the latitude of Verkhoturye form a natural gateway into Siberia from the west. With the Russian conquest of Siberia and the foundation of the trans-Ural Russian towns of Tyumen in 1586 and Tobolsk in 1587 the problem arose of finding the best route to them from European Russia. Around 1580, Yermak Timofeyevich had ascended the Chusovaya River south of Verkhoturye and crossed to the Barancha, a tributary of the Tagil River. This route was abandoned because the upper Tagil was too shallow. Around 1590 a more northerly route was opened from Cherdyn north of Solikamsk up to the Vishera River and down the Lozva River. In 1597 Artemy Babinov pioneered what became the standard route. This Babinsky Road ran overland from Solikamsk on the western slope of the Urals to Verkhoturye. An "ostrog" (fort) was built at Verkhoturye in 1598 and a customs house in 1600 or 1601. Until about 1763, Babinov's route was the main road into Siberia. All winter sledges would haul goods from Solikamsk to Verkhoturye where they were stockpiled until the spring thaw. Siberian furs collected as "yasak" (tribute) passed through Verkhoturye "en route" to the Sable Treasury in Moscow. Privately owned furs leaving Siberia paid a 10% tax unless the merchant could prove that the tax had been paid in Siberia. Goods entering Siberia paid a 4% tax (in addition to the 10% paid when the goods were sold). Goods coming and going were inspected and inventoried to prevent contraband. Guard posts were set up in the region to prevent people from slipping around the custom house.