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Timeline History The Kharkiv Locomotive Factory ( KhPZ ) built about 20 % of the Russian Empire 's railway engine s. After the Russian Revolution and the establishment of the Soviet government in Ukraine , the factory was put to work designing and building tractor s and , after 1927 , tank s. The Leningrad 's Bolshevik Factory and the Kharkiv 's KhPZ in 1929 became the first two Soviet tank factories to be modernized with German assistance under the Treaty of Rapallo , 1922 .
 Kharkiv, Factory, Russian Empire, Soviet government in Ukraine, Leningrad, Factory, Kharkiv, German
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Kharkiv, Factory, Russian Empire, Soviet government in Ukraine, Leningrad, Factory, Kharkiv, German