Manchuria was where Chiang Kai-shek lost China to Mao. Thereafter, Mao swept south below the Yangtze to destroy the Nationalist armies south of the river.
Manchuria as a region does not exist anymore. It is now divided into the provinces of Liaoning, Jilin, and Heilongjiang.
In this 2015 book, Where Chiang Kai-shek Lost China, Harold M. Tanner, Tanner, in his final chapter, concluded that the war was not lost due to the withholding of military supplies and aid from the Americans.
I am not sure if this is an accurate conclusion. The supplies were there, but too far away. The Americans could have sent supplies directly by air.
Tanner revealed that the Americans did not wish to pump in massive aid or soldiers to help Chiang, as they foresaw that Mao would come and beg the Americans for help to rebuild China.
He argued that the Nationalist generals were poor commanders compared to Lin Biao.
Mao was the strategist. Lin Biao executed the war plans. Both deserve credit for winning the war in Manchuria.