roughly the southern half (Jinzhou District and south) of present-day Dalian. Japanese invested heavily in the region, which became the main trading port between Manchuria and Japan. Japan leased the area from Manchukuo after establishing that puppet state in 1932. In 1937, as the Second Sino-Japanese War began, Japan enlarged and modernized the trade zone as two cities: the northern Dairen (Dalian) and the southern Ryojun (Lüshun or Port Arthur). Post-World War II With the unconditional surrender of Japan in August–September 1945, Dairen passed to the Soviets, whose Manchurian Strategic Offensive Operation had liberated the city on 22 August 1945. The Soviets and Chinese Communists cooperated to develop the city, relatively undamaged during the war, especially its industrial infrastructure and the port. The Soviet government rented the port and in 1945 the first Chinese Communist mayor of the new Lüda Administrative Office () was appointed. In 1950 the USSR presented the city to the Chinese Communist government without any compensation. Dalian and Lüshun (former Port Arthur) merged as Lüda on 1 December 1950. From 12 March 1953 to 1 August 1954 it was a direct-controlled municipality and not part of Liaoning. Soviet troops left the city in 1955. After the Soviets left, the PRC made Lüda a major shipbuilding center. In 1981 the city was renamed Dalian, with Lüshunkou becoming a constituent district. In 1984 the Chinese Government designated the city a Special Economic Zone. At the time, Dalian was China's largest foreign-trade port. 1990 to present The city was upgraded from a prefecture-level city to a sub-provincial city in May 1994, with no change in its administrative subdivisions. In the 1990s the city benefited from the attention of Bo Xilai (later Party secretary of Chongqing). Bo served both as the mayor of the city and as one of the major leaders in the province; among other things, he banned motorcycles and planted large, lush parks in the city's many traffic circles. He also preserved much of Dalian's Japanese and Russian architectural heritage. He also worked as the former Minister of Commerce of China. Since 2007 Dalian has hosted the Annual Meeting of the New Champions ("Summer Davos"), organized by the World Economic Forum, in alternating years with Tianjin. The venue for the forum is the Dalian International Conference Center in Donggang CBD. In 2008 about 1,000 people protested and blocked traffic as a response to the 2008 Tibetan anti-Chinese