Since some foreign paid posters infiltrated in this forum are hell bent spewing historical nonsense while letting loose a spate of invectives against a rare and genuine friend of Pakistan, far from derailing the original thread, some clarifications are needed.
So who saved who during the 1936-1945 period, that overlaps the official WWII period?
The Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan from July 7, 1937, to September 9, 1945. It began with the Marco Polo Bridge Incident in 1937 in which a dispute between Japanese and Chinese troops escalated into a battle.
Initially the Japanese scored major victories, capturing both Shanghai and the Chinese capital of Nanking in 1937. After failing to stop the Japanese in the Battle of Wuhan, the Chinese central government was relocated to Chongqing (Chungking) in the Chinese interior. By 1939, after Chinese victories in Changsha and Guangxi, and with Japan's lines of communications stretched deep into the Chinese interior, the war reached a stalemate. The Japanese were also unable to defeat the Chinese communist forces in Shaanxi, which waged a campaign of sabotage and guerrilla warfare against the invaders. While Japan ruled the large cities, they lacked sufficient manpower to control China's vast countryside.
Notice that at this point, when loosing 3 times its capital, the Republic of China did never surrender, unlike the feable West too prone to capitulate after an even shorter engagement:
Poland (who fought only from September 1 to September 27, 1939)
Finland (who only fought from November 30, 1939 to March 12, 1940)
Holland (who fought only from May 10, 1940 to May 15, 1940)
Belgium (who fought only from May 10, 1940 to May 28, 1940)
Norway (who fought only from April 9, 1940 to June 10, 1940)
France (who fought only from September 3, 1939 to June 22, 1940)
Yugoslavia (who fought only from April 6, 1941 to April 17, 1941)
Greece (who fought only from October 28, 1940 to April 27, 1941)
In 1944 Japan launched the invasion, Operation Ichi-Go, that conquered Henan and Changsha. However, this failed to bring about the surrender of Chinese forces. In 1945, the Chinese Expeditionary Force resumed its advance in Burma and completed the Ledo Road linking India to China. At the same time, China launched large counteroffensives in South China and retook West Hunan and Guangxi.
Despite continuing to occupy part of China's territory, Japan eventually surrendered on September 2, 1945.
This means that Japanese loss in manpower in China during the conflict from 1937 to 1945 amounted to 1.77 million deads, 1.9 million wounded, totaling: 3,670,000 (ROC estimate).
Considering that Operation Barbarossa, the Axis invasion of the Soviet Union, starting on 22 June 1941, during World War II, involved 3.8 million personnel (Initial Axis armies frontline strength), and that Japan had already considered an invasion of the Soviet Union such as in the "Northern Expansion Doctrine" (北進論, Hokushin-ron or Northern Road), a pre-World War II political doctrine of the Empire of Japan which stated that Manchuria and Siberia were Japan's sphere of interest and that the potential value to Japan for economic and territorial expansion in those areas was greater than elsewhere, it is only due to the Chinese people's heroic resistance that Japan could no longer seize this golden opportunity and launch a simultaneous assault on the USSR from the East, when Operation Barberossa started in the European theater of operation.
Indeed, as ~1.5 millions Japanese military personnels were already stucked for seven years in the Chinese quagmire!
Needless to add that a pincer movement from the Japanese in Siberia would have made impossible the Soviet's decisive reinforcement composed of some 30 divisions of Siberian troops freed from the Soviet Far East, that launched a massive counterattack as part of the Soviet winter counteroffensive, and pushing the German armies back 100–250 km from Moscow.
Not to mention the relocation of soviet factories in the East that allowed the USSR to continue its vital industrial production!
Conclusion
China as the first nation to enter the war as earlier as 1937, by opposing an unexpected all out resistance to the Japanese Empire, has jeopardized the Japanese possibility to wage a simultaneous war on the Soviet Union in 1941, which would have been ultimately fatal to the USSR.
By surrendering quickly like the other European cowardly nations, the Republic of China could have avoided the deaths and destructions, and being a puppet of Japan, could have sent its armies as cannon fodders in the invasion of the USSR, just like Manchukuo and Menkukuo, thus making the Soviet's resistance futile.
The Soviet Union owes a lot to the Chinese people, who lost officially 37 millions people, amounting to 40 percent of WWII total casualties. Denying this fact is an insult to the memory of the martyrs, who did suffer the worst massacres as in Nanjing, biological warfare, chemical warfare, mind-control warfare, directed energy warfare, and even being slaughtered as human guinea pig in live biological experiments.
Sources:
https://en.wikipedia.org/wiki/Second_Sino-Japanese_War
http://www.historyplace.com/worldwar2/timeline/ww2time.htm
https://en.wikipedia.org/wiki/Operation_Barbarossa
https://en.wikipedia.org/wiki/Soviet–Japanese_Neutrality_Pact
https://en.wikipedia.org/wiki/Hokushin-ron
https://forum.axishistory.com//viewtopic.php?t=22442
http://www.360doc.com/content/06/0314/02/5368_79419.shtml
The Manchuria Airplane Manufacturing Company was established in late 1938 under the supervision of the Japanese government[2] as a subsidiary of the Nakajima Aircraft Company of Japan. Its main plant was located in Harbin, Manchukuo.
From 1941 to 1945, Manshū produced a total of 2,196 airframes (eighth among Japanese airframe manufacturers), of which 798 were combat aircraft. The company also produced 2,168 aircraft engines (sixth among Japanese aircraft engine manufacturers). In addition, Manshū provided repair services for a variety of aircraft in the Manchukuo Air Force and for Imperial Japanese Army Air Force units stationed in Manchukuo.
The Red Army confiscated the company's factory and equipment in 1945 at the end of World War II, and the Soviets took much of its equipment back to the Soviet Union.
https://en.wikipedia.org/wiki/Manchuria_Airplane_Manufacturing_Company
From the above we see that it is the opposite, the assembly lines are going from China's Far East toward the Soviet Union! And that led later to official complains from the PRC toward the USSR.