Greetings! How fortuitous that I just finished an in-depth historiographical reading and essay on the Sino-Soviet Split! This major International Relations event of the Cold War is actually something that remains under debate in western and eastern academia, so you have touched on an interesting (and often overshadowed) topic of the Cold War indeed. Let's see what light I can bring on the matter.

Red Star Over China

The origins of the Sino-Soviet Split can actually be traced as as far back as the Chinese Civil War's end in 1949, when Mao Zedong and the Communist Party of China (CPC or CCP) proclaimed the People's Republic of China in Beijing on October 1st. Many historians have analysed the role of Mao as a crucial instigator in the split and the ideological persona of the Chinese Communists. By this time Mao had already formally adopted his own branch of Marxist-Leninist thought, known as Maoism. In Mao's ideological splinter of Communism, it was the peasants in the countryside, and not the urban proletariat (or working class) who would spearhead the great socialist revolution. This contrasted sharply with Joseph Stalin and the CPSU's belief that the urban proletariat and mass industrialisation were the keys to the socialist utopia. Though of course, ideological divergences at this time were of little consequence, as both countries were in vastly different economic states in 1949 (over 80% of China's populace remained in the peasant farming class, whilst the USSR had a more urbanized workforce).

Mao and the CPC personally viewed Stalin as the great hero of Bolshevism and the Communist movement worldwide, who had carried on with the fulfillment of the vision which Lenin had initially started in 1917. Here's a fairly extract from an official document written by the CPC press (the Hongqi or Red Flag) titled "On the Question of Stalin".

Stalin fought tsarism and propagated Marxism during Lenin’s lifetime; after he became a member of the Central Committee of the Bolshevik Party headed by Lenin; he took part in the struggle to pave the way for the 1917 Revolution; after the October Revolution he fought to defend the fruits of the proletarian revolution.

Stalin led the CPSU and the Soviet people, after Lenin’s death, in resolutely fighting both internal and external foes, and in safeguarding and consolidating the first socialist state in the world.

Stalin led the CPSU and the Soviet people in upholding the line of socialist industrialization and agricultural collectivization and in achieving great successes in socialist transformation and socialist construction.

Stalin led the CPSU, the Soviet people, and the Soviet army in an arduous and bitter struggle to the great victory of the anti-fascist war.

Stalin defended and developed Marxism-Leninism in the fight against various kinds of opportunism, against the enemies of Leninism, the Trotskyites, Zinovievites, Bukharinites, and other bourgeois agents.

Stalin made an indelible contribution to the international communist movement in a number of theoretical writings which are immortal Marxist-Leninist works.

Stalin led the Soviet Party and Government in pursuing a foreign policy which on the whole was in keeping with proletarian internationalism and in greatly assisting the revolutionary struggles of all peoples, including the Chinese people.

Stalin stood in the forefront of the tide of history guiding the struggle, and was an irreconcilable enemy of the imperialists and all reactionaries.

Stalin’s activities were intimately bound up with the struggles of the great CPSU and the great Soviet people and inseparable from the revolutionary struggles of the people of the whole world.

Stalin’s life was that of a great Marxist-Leninist, a great proletarian revolutionary.^(1)

A lengthy extract, but most indicative of the CPC's positive view of Stalin. Now historians do also note that Mao and Stalin may have had some early mistrust amongst them. When they first met in Moscow in 1950, the resulting Treaty of Friendship, Alliance, and Mutual Assistance solidified the positive (if, some may argue, superficial) relations between these giants of the Communist bloc. Among other things, the Treaty promised a loan of $300 million from the USSR to the PRC, which it used to kickstart the First Five Year Plan. One might assume that such a treaty would assure constant friendship between the two nations, but that was not to be the case. Early ripples were felt later that year...

The Question of Korea

In 1950, the Korean War broke out, and the Sino-Soviet Alliance was split on the extent of their aid to the DPRK. On the one hand, Mao and the CPC were eager to lend full armed support, going so far as to order 500,000 troops of the People's Liberation Army to march across the Yalu River in October 1950 to assist the struggling North Korean Army. The USSR on the other hand, very reluctantly provided limited air support and economic materiel, despite Mao (and Kim Il Sung's) constant requests to Stalin that he deploy the Red Army on the peninsula. Herein we find the seeds of a key point of divergence beyond the ideological one mentioned earlier: geopolitical strategy.

Mao and the CCP were all for a concept often called "Permanent Revolution", in which the Communist states would have to actively fight against the imperialist-capitalist enemies in order to spread the revolution across the globe. Mao himself famously remarked that these powers were "paper tigers", and shared the following rhetoric:

"Only when imperialism is eliminated can peace prevail. The day will come when the paper tigers will be wiped out. But they won't become extinct of their own accord, they need to be battered by the wind and the rain."^(2)

The "wind and rain" in this instance, represented the force of the Communist bloc. Stalin and the CPSU however, did not share Mao's openly confrontational view of the imperialist-capitalists. They preferred (and this was actually a key part of Stalinist thought), the opposite policy of "Socialism in One Country", which essentially is what it says on the tin. The spark which blew up a true fury of debate, and eventually led to the split however, came on the 24th of February, 1956.

On The Cult of Personality and Its Consequences

During the 20th Congress of the CPSU, Premier Nikita Khrushchev delivered his so-called "Secret Speech", denouncing the ideas of Stalin and commenting harshly on the Stalinist policies the USSR had come to adopt. With Khrushchev now in control, he led the Soviet Union away from these policies, towards his "revisionist" policies, including "Peaceful Coexistence" with the United States. This move absolutely angered Mao and the CPC, who were quick to publish works decrying the speech and speak out at International Communist Movement Meetings. In the sources is an excellent website which contains external links to translations of those speeches and works, it is highly recommend to read through a few of them. For the purpose of (attempted) concision, here is John Lewis Gaddis on the significance of the speech:

"he [Mao] argued that the USSR was losing its revolutionary edge, the true revolutionary country, China, would not make the same mistake."^(3)

Further, the CPC viewed Khrushchev's cooler view of the US as "capitulationist", and a complete betrayal of the Marxist-Leninist cause. Khrushchev for his part, "opposed and feared Mao's militant and unyielding Anti-Americanism."^(4) This infighting within the Communist bloc went back and forth over the ideological, geopolitical, and even military issues until it culminated in a 1969 border war between the USSR and PRC.

The Bomb

Another topic of divergence between the two powers was nuclear weaponry. The USSR had initially been eager to cooperate with the PRC, going so far as to send advisers throughout the late 1950s and provide prototypes of some atomic weapons. This response will not delve too far into those efforts, but they do make for an interesting side investigation. However, Khrushchev, in implementing his idea of Peaceful Coexistence, pursued arms negotiations with the western powers, and in 1960 withdrew all Soviet technical advisers and support for the Chinese nuclear program. Vladislav Zubok on this point:

"Khrushchev's vision of nuclear bipolarity [US and USSR possession] became anathema [something of hatred] for Mao, because it relegated China to a secondary position in the pecking order of great powers."^(5)