In China, the Khingan mountains are divided into the Greater Khingan and Lesser Khingan. The Lesser Khingan range runs roughly from the northwest to the southeast and separates the valley of the Amur (Heilongjiang) River from that of the Nenjiang River. The mountain range then turns toward the east and north-east, entering Russia.2 The Amur/Heilongjiang, which is a border river, forms a gorge when crossing the mountain range.
Малый Хинган; Great Soviet Encyclopedia in 30 volumes — Ch. ed. A.M. Prokhorov. - 3rd edition - M. Soviet Encyclopedia, 1969-1978. (in Russian) http://bse.sci-lib.com/article073174.html ↩
Еврейская автономная область - Географическое положение и рельеф https://www.eao.ru/o-eao/obshchie-svedeniya/geograficheskoe-polozhenie-i-relef--1/ ↩