The [Russian] revolution was followed by the Civil War which lasted to 1922, and during this conflict few ethnic groups supported the Communist Red Army with the same devotion and enthusiasm as the Koreans.
Some 8,000 Koreans joined the Red forces. This might not appear to be a large number, but the ethnic Korean community was roughly 100,000 strong in 1917, so it means that roughly one out of four able-bodied males joined the Communist army.
In most cases these people were volunteers, not draftees: for a long time, the Russian Far East was beyond the reach of the regular Red Army, so operations were conducted largely by guerrillas who relied on wide popular support.
At the same time, there were very few ethnic Koreans who chose to fight on the other side, with the anti-Communist Whites.
Such enthusiasm for the militant left was easy to explain. First, the battle cry of the Communists was “land to the farmers!” Most Koreans were farmers, but they often faced serious discrimination.
Russian authorities preferred to give land to the ethnic Russian settlers whose plots were then often toiled by Korean tenants. The Communists explicitly promised to change the situation by distributing land equally among all people who needed it.
Second, Koreans faced a certain amount of discrimination in old Russia, and Communists, being patiently anti-imperialist and anti-racist, promised that in a Communist Russia there would be no ethnic or racial discrimination whatsoever.
Third, in the Russian Far East the anti-Communist forces were supported and supplied by the Japanese. A large Japanese expeditionary force was actually dispatched to Siberia.
Taking into consideration that most Korean intellectuals (and nearly all politically active Korean leaders) had been active in the national liberation movement, they naturally enough became allies with their enemies’ enemy, that is with the Reds ― even if they did not initially harbor much sympathy for the Communists’ radical social program.
Thus, the Koreans entered the red guerrilla ranks in large numbers ― and in the early Communist armies they knew how to indoctrinate soldiers.
A number of those people, especially Russian speakers, soon became devoted Communists and active propagandists of the new teaching among their fellow Koreans.
The first prominent leader of the Korean Communists was a woman, Alexandra Stankevich (Nee Kim). Actually, she was more Russian than Korean in culture and education.
Her Korean father, a fluent Russian speaker and a professional interpreter, died when she was very young, and the girl was adopted by her father’s friend and his Russian family.
Alexandra received a good education, married (unhappily) a Russian man whom she later divorced, and traveled far across Russia.
From around 1915 she became very involved with underground socialist politics. In 1917-18 she was a prominent Communist leader in the maritime province and also a chief foreign policy negotiator for the local Communist government.
When in 1918 the government was overthrown by the Whites and their Japanese allies, Alexandra Kim was captured and killed.
Around the time of Alexandra Kim’s death, Yi Tong-hwi, a former officer of the Korean army, and by then a guerrilla commander, established the first Korean Communist group, called the Korean Socialist Party.
This happened in the city of Khabarovsk, and most party members were local Russian Koreans. Soon afterward, Yi Tong-hwi was even invited by Lenin to have a discussion about the Korean situation, in Moscow, and his small group became the first sprout of the Korean Communist movement, which for better or (more likely) worse influenced Korean history for the next hundred years.