Well, it was time for something dramatic.
Stalin's Foreign Policy in East Asia
...two Soviet politicians in particularly suffered greatly from the failure of Mao’s Chinese Communists to conclusively defeat Chiang Kai-Shek; the two Soviet politicians who insisted that Mao was a sure winner - Laventry Beria and Anastas Mikoyan. Both were fired from their positions and expelled from the Communist Party. Mikoyan, already having garnered Stalin’s distrust for publishing a wartime speech of Churchill’s that reflected poorly on Stalin, was summarily executed after a fraudulent show trial. The paranoid Stalin sought buffer states to “protect” the Soviet Union from foreign invaders. The client states in Eastern Europe established this well. If there was a war with the West, it would be waged in Germany and Poland. However, the People’s Republic of China didn’t actually block off Republican China. Worst of all, it permanently poisoned relations with Chiang Kai-Shek, which Stalin thought was salvageable before the split. However, Stalin knew he couldn’t back off from Red China, or else the other Communist satellites would lose faith. He had seen how quickly Nazi Germany’s allies had turned against Hitler in 1944 and 1945 once the Soviet Union gained upper-hand.[...]
...Stalin grew even more erratic after his stroke in March of 1953.[1] He ordered Molotov purged and executed, although the wily Communist was visiting Chairman Lin at the time and chose not to return. The Chinese did not return him. Stalin almost ordered an invasion of Communist China, but was dissuaded by General Zhukov, who was nevertheless fired from his position and removed from the Communist Party (though not killed).
Stalin was essentially mollified and with Molotov out of the picture, he focused on another imaginary threat: the Jewish doctors that supposedly "poisoned" him. By then, Stalin had forgotten his earlier hatred of Beria, and knowing his expertise in ethnic cleansing, welcomed Beria back to the Communist Party to “deal with the Jews."[2]
Despite not being morally opposed to well, anything, Beria thought a mass ethnic cleansing of Jews was strategically unwise, even though it was Stalin's antisemitic paranoia that had revived his political career. Stalin’s plan involved deporting them all to labor camps in Central Asia or Siberia, but Beria was aware that this would immediately create parallels to the Holocaust, which the Soviet Union condemned as a great evil that the Red Army destroyed. The status of the Red Army as the liberators of Auschwitz was very important to both the Soviet Union's domestic and international image.
Instead, Beria sought to deport them to friendly client states or Soviet Republics and spinning the deportations as “economic assistance.” Deporting them to a non-Communist bloc nation was out of the question, but Beria hoped he could mollify both Stalin and global condemnation by just sending them to a client state. However, acting independently of Stalin, Beria had relatively little leverage. Beria called a meeting of all the Communist Secretaries of the Soviet Republics, hoping that one of them would be willing to accept the over two million or so Jews. None accepted. Beria then called a meeting of important leaders, especially those with NKVD ties, of the Soviet client states.
Not only did they all decline, but Beria was told to his face by Jakub Berman and Hilary Minc, the two NKVD veterans and Jewish members of Communist Poland’s triumvirate, that Poland was not going to accept a single Jewish refugee. Berman and Minc were both terrified that Stalin’s anti-Jewish purge would target them next and worked as assiduously as possible to underplay their Jewish heritage.
In his desperation, Beria phoned three more Communist leaders: Kim Il-sung of North Korea, Sanzo Nosako of North Japan, and Lin Biao of North China. Kim flatly refused. Sanzo, with stronger humanitarian impulses than any of the other Eastern bloc leaders, indicated he would accept up to 100,000 refugees on a temporary basis, an impressive commitment considering North Japan only had 13 million residents. Lin Biao apparently shrugged and redirected Beria to his foreign minister, Wang Jiaxiang. Wang, who had studied in Moscow as a college student (and presumably interacted with many Russian Jews), immediately committed to taking any Jewish deportees. Beria was shocked and thought it ironic that Soviet Jews would now be headed towards a country directly next to the distinctly non-Jewish Jewish Autonomous Oblast.
Surprisingly, Wang’s proposal basically garnered no response in the Communist Party, neither positive nor negative. The vast majority of the Politburo were military men, not intellectuals, and few actually knew what a “Jew” was, other than having a vague notion that Hitler wanted to kill them all for some reason. As Hitler was a fascist, these men concluded that these “Jews” had to be alright chaps. Not to mention Mao Zedong had impressed onto everyone that an outnumbered Communist China needed more people in order to take down the KMT menace to the South, and it seemed like people were dropping into their lap[...]
...under Beria’s watch, over two million Soviet Jews were shipped to the East across the Trans-Siberian Railroad, often in deeply dehumanizing, crowded, and unsanitary cattle cars. Tens of thousands died in deeply inhumane conditions and the survivors were unceremoniously dumped in a foreign frozen wasteland, where almost none spoke the local language and were placed under the tyrannical control of stern Communist Party of China political commissars. Thousands more died when a particularly virulent strain of bubonic plague struck the refugees in their unsanitary conditions.[3] In one particular instance of Communist mismanagement, many political commissars were not aware that not all of the deportees were Russian-speaking, unaware that there were other types of Soviet Jews, which meant miscommunication and mutual recriminations were common. Global condemnation quickly rolled in, but failed to rise to crisis levels.
That being said, the Jewish refugees were a Communist economic planners dream - a relatively high-education population (at least by the extremely low standards of a country with over 90% illiteracy) with no meaningful ability to revolt. One of the most powerful men in Communist China, the Stalinist Gao Gang, frustrated at the failure of agricultural collectivism, quickly took personal charge of the deportees, organizing them in model agricultural collectives and Stalinist-style industrial towns, mirrored after Magnitogorsk in the USSR, scattered throughout the People’s Republic, often at rail hubs. Most communities near railways in Northeastern China had already been pretty used to foreigners, especially Russians, due to the long history of Imperial Russian intervention and railway ownership. In fact, rail in Northeastern China was almost entirely based on the Russian wide-gauge, as opposed to the Anglo-Japanese-style thin gauges in the rest of China. These tightly-run, totalitarian, and often internall segregated industrial model cities quickly became one of the defining traits of Northeastern China's Communist system.
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[1] I’m going off the Beria killed Stalin theory, not because it’s particularly convincing (we really have no idea what happened), but because it’s more interesting.
[2] OTL Beria masterminded the deportations of many Soviet minorities, such as the Crimean Tatars.
[3] Northeastern China was the last bastion in the world of bubonic plague, with the last cases recorded in 1960.