evidence: A large river delta between the Ussuri and Amur rivers (or the Heilongjiang and Wusuli rivers, in Mandarin Chinese) is the site of a series of serious challenges between China and Russia for many centuries. The delta is almost 350 km2 in area and is located very close to Khabarovsk, the capital city of the Russian Far East. It includes two sparsely inhabited islands, called Bolshoi Ussuriiski and a smaller Tarabarov island (as known in Russian) or Heixiazi and Yinlong, respectively (in Mandarin). This remote delta area has been occupied by Russia since 1929, but China has maintained its claims to this territory. Deadlock over the future of this region has proved to be the main obstacle towards the full resolution of Sino-Soviet border disputes for various decades. The dispute led to the Zhenbao/Damanskii military clash in 1969 and drove the two countries to the edge of a nuclear war. Since 2004, a ‘fifty-fifty’ solution has finally been implemented and agreed to by both sides. [...] China Military News. 2010. Heixiazi island to become major joint China—Russian tourist resort. 26 November. http://www.china-defense-mashup.com/heixiaziisland-to-become-major-joint-china-russian-tourist-resort.html [...] Iwashita, A. (2013). Bolshoi Ussuriiski/Heixiazi.