Symon Petliura in the context of "Treaty of Warsaw (1920)"

The Ukrainian People's Republic (UPR) was a short-lived state in Eastern Europe. Prior to its proclamation, the Central Council of Ukraine was elected in March 1917 as a result of the February Revolution, and in June, it declared Ukrainian autonomy within Russia. Its autonomy was later recognized by the Russian Provisional Government. Following the October Revolution, the Central Council of Ukraine denounced the Bolshevik seizure of power and proclaimed the Ukrainian People's Republic with a territory including the area of approximately eight Russian imperial governorates (Kiev, Volhynia, Kharkov, Kherson, Yekaterinoslav, Poltava, Chernigov and Podolia). It formally declared its independence from Russia on 22 January 1918.

During its short existence, the republic went through several political transformations – from the socialist-leaning republic headed by the Central Council of Ukraine with its general secretariat, to the socialist republic led by the Directorate and by Symon Petliura. Between April and December 1918, the socialist authority of the Ukrainian People's Republic was suspended, having been overthrown by the pro-German Ukrainian State of Pavlo Skoropadskyi, who was elected as the Hetman of Ukraine by a congress of peasants. After the collapse of the Ukrainian State, the Ukrainian People's Republic declared its unification with the West Ukrainian People's Republic in January 1919. After the Polish–Ukrainian War, it signed an alliance with the Second Polish Republic. On 10 November 1920, the state lost the remainder of its territory to the Bolsheviks. The Peace of Riga on 18 March 1921 between Poland, Soviet Russia (acting also on behalf of Soviet Belarus), and Soviet Ukraine sealed the fate of the Ukrainian People's Republic.

The Polish–Soviet War (14 February 1919 – 18 March 1921) was fought primarily between the Second Polish Republic and the Russian Soviet Federative Socialist Republic, following World War I and the Russian Revolution.

After the collapse of the Central Powers and the Armistice of 11 November 1918, Vladimir Lenin's Soviet Russia annulled the Treaty of Brest-Litovsk and moved forces westward to reclaim the Ober Ost regions abandoned by the Germans. Lenin viewed the newly independent Poland as a critical route for spreading communist revolutions into Europe. Meanwhile, Polish leaders, including Józef Piłsudski, aimed to restore Poland's pre-1772 borders and secure the country's position in the region. Throughout 1919, Polish forces occupied much of present-day Lithuania and Belarus, emerging victorious in the Polish–Ukrainian War. However, Soviet forces regained strength after their victories in the Russian Civil War, and Symon Petliura, leader of the Ukrainian People's Republic, was forced to ally with Piłsudski in 1920 to resist the advancing Bolsheviks.