Northeast China or Northeastern China () is a geographical region of China, which is often referred to as "Manchuria" or "Inner Manchuria" by surrounding countries and the West. It usually corresponds specifically to the three provinces east of the Greater Khingan Range, namely Liaoning, Jilin, and Heilongjiang, but historically is meant to also encompass the four easternmost prefectures of Inner Mongolia west of the Greater Khingan. The heartland of the region is the Northeast China Plain, the largest plain in China, with an area over . It is separated from Russian Far East to the north by the Amur, Argun, and Ussuri rivers; from Korea to the south by the Yalu and Tumen Rivers; and from Inner Mongolia to the west by the Greater Khingan and parts of the Xiliao River. Due to the shrinking of its once-powerful industrial sector and decline of its economic growth and population, the region is often referred to as China's Rust Belt. As a result, a campaign named Northeast Area Revitalization Plan was launched in the 2000s by the State Council of the People's Republic of China, in which five prefectures of eastern Inner Mongolia, namely Hulunbuir, Hinggan, Tongliao, Chifeng and Xilin Gol, are also formally defined as regions of the Northeast. Names Northeastern China is known in Chinese contexts as simply the Northeast or, from the Mandarin pronunciation of its Chinese name, as Dōngběi. The area has long been known in Indo-European languages as Manchuria, as it was the homeland of the Manchu people who established and ruled the Qing dynasty of China from the 17th to early 20th century. The name was not used by the Qing government itself, who called the area their "Three East" or "Eastern Provinces", and its use is discouraged by the People's Republic of China, which associates the exonym with Manchukuo, a puppet state of Imperial Japan, though these are separate terms in most languages. It is known more specifically as when it needs to be distinguished from Outer Manchuria, which was ceded by Qing China to the Russian Empire through the Amur Annexation in the 1850s. Historically, the area was also known as Liaoyang (from its capital at Liaoyang) under the Yuan; as Nurgan (from its capital at Tyr) under the Ming dynasty; and as Guanwai () or Guandong (), meaning "Lands beyond" or "Lands East of the Pass" in reference to the strategic Shanhai Pass