What nations troops were battled by both the communists and the nationalist because this nation was seen a a common enemy?

The nation whose troops were battled by both the communists and the nationalists in China was Japan. During the Second Sino-Japanese War (1937-1945), both the Chinese Communist Party and the Kuomintang (Nationalists) united to resist Japanese Imperialism, viewing the Japanese forces as a common enemy. This temporary alliance helped them to focus on defeating Japan, despite their ongoing civil conflict. After the war, tensions between the two factions resumed, leading to the Chinese Civil War.