中原大戰
Despite the reunification, there were still ongoing conflicts across the country. Remaining regional warlords across China chose to cooperate with the Nationalist government, but disagreements with the Nationalist government and regional warlords soon broke out into the Central Plains War in 1930. Northwest China erupted into a series of wars in Xinjiang from 1931 to 1937. Following the Xi'an Incident in 1936, efforts began to shift toward preparation of war against the Japanese Empire.