Ridder, formerly known as Leninogorsk is a city in the East Kazakhstan Region in north-eastern Kazakhstan. Its population is approximately 50,500. The city is situated in the south-western Altai Mountains and north-east of the region's capital, Oskemen, along the Ulba River, at an elevation higher than 700 metres.

East Kazakhstan Region is a region of Kazakhstan. It occupies the easternmost part of Kazakhstan, and includes parts of the Irtysh River, Lake Markakol, and Lake Zaysan. Its administrative center is Öskemen. The region borders Altai Krai and Altai republic in Russia in the north and northeast and the People's Republic of China, via Xinjiang, in the south and southeast. The easternmost point of the Oblast is within about 50 kilometres of the westernmost tip of Mongolia; however, Kazakhstan and Mongolia do not share a common border, the two countries being separated by a small part of Russia and China.