Oskemen or Ust-Kamenogorsk (pop. 320,000) is the administratove center of the East Kazakhstan Province of Kazakhstan.
Founded in 1720 at the confluence of the Irtysh and Ulba rivers as a fort and trading post named Ust-Kamennaya. The city was established in 1720 according to the order of the Russian Emperor Peter the Great, who sent a military expedition headed by major Ivan Vasilievich Likharev in the search of Yarkenda gold. Likharev’s expedition directed up the Irtysh river to Zaysan Lake. There, at the confluence of the Ulba and the Irtysh rivers the new fortress was laid – the Ust-Kamennaya Fortress. The Ust-Kamennaya Fortress appeared on the map of the Russian Empire, the very southern end of the Irtysh line.
The city developed into a major mining and metallurgical center during the Soviet period. Mining of non-ferrous metals, especially uranium, beryllium, tantalum, copper, lead, silver and zinc remain important.