The Indigirka (; ) is a river in the Sakha Republic in Russia between the Yana to the west and the Kolyma to the east. It is long. The area of its basin is . History The isolated village of Russkoye Ustye, located on the delta of the Indigirka, is known for the unique traditional culture of the Russian settlers whose ancestors came there several centuries ago. Some historians have speculated that Russkoye Ustye was settled by Pomors in the early 17th century. In 1638 explorer Ivan Rebrov reached the Indigirka. In 1636–42 Elisei Buza pioneered the overland route to the Indigirka river system. At about the same time, Poznik Ivanov ascended a tributary of the lower Lena, crossed the Verkhoyansk Range to the upper Yana, and then crossed the Chersky Range to the Indigirka. In 1642 Mikhail Stadukhin reached the Indigirka overland from the Lena. Zashiversk on the Indigirka was an important colonial outpost during the early days of Russian colonization. It was subsequently abandoned in the 19th century. Other historical settlements, now long abandoned, were Podshiversk and Uyandinskoye Zimov'ye. In 1892–94 Baron Eduard Von Toll carried out geological surveys in the basin of the Indigirka (among other Far-eastern Siberian rivers) on behalf of the Russian Academy of Sciences. During one year and two days the expedition covered , of which were up rivers, carrying out geodesic surveys en route. Course It originates at the confluence of the long Tuora-Yuryakh (also known as Khastakh, Khalkan or Kalkan) river and the long Taryn-Yuryakh, both of which originate on the slopes of the Khalkan Range. In its higher course, the river flows northwestwards along the Yana-Oymyakon Highlands, through the lowest part of the Oymyakon Plateau. Turning north, it cuts through several subranges of the Chersky Range. At the point where it crosses the Chemalgin Range the river narrows and flows into a deep gorge, forming rapids. Where it is joined by the Moma river from the southeast, the Indigirka reaches the Momo-Selennyakh Depression, a wide intermontane basin and the middle course of the river begins, where its valley expands. Turning northwards, the Indigirka cuts deeply across the Moma Range and flows northeastwards meandering across the Aby Lowland and widening to . After flowing between the neck formed by the eastern end of the Polousny Range and the western end of the Ulakhan-Chistay Range, it flows north with the Kondakov Plateau to