That would depend on whether you mean communists as in the politcal entity headed by Mao or communists as in people who believe in the theories of Marx and Engles. As Mao's communist party worked with the KMT and communists worked in the KMTgovernment as ministers and beuaraucrats. As ordered by the leader of the international communits revolution in moscow. Until Chiang went fascist and got his blue shirts (inspired by the Italian black shirts and German brown shirts) to purge the communits. And Sun founded a revolutionary party that wasn't the KMT (I don't remember the name but i do remember that it wasn't even called the KMT) in 1894 in exile. The KMT comes later after (around 1920) Sun returns to China.