Before the 17th century, the boundaries between Mongolia, China, and Russia had not been well defined. Starting in the middle of the 17th century, clashes erupted between Qing forces and Russian settlers and prospectors along the borders of Manchuria. The Qing dynastys collapse in 1911 offered Mongols an opportunity to liberate themselves, a possibility that they, in part, subverted by aligning too closely with Russia. Beginning in the early 1980s, China and the Union of Soviet Socialist Republics (USSR) began to move toward a reapprochement, which naturally influenced Mongolia's relations with China. The involvement of the USSR shaped many of Mongolia's territorial issues. The onset of the Chinese Cultural Revolution, especially as it affected Inner Mongolia, generated even greater animosity between China and the Mongolian People's Republic (MPR). However, Chinas increasing assertiveness in 2010 in dealings with Japan and its Southeast Asian neighbors about disputed islands and territorial waters may presage greater difficulties on Sino-Mongol border issues.