Holodomor Wikipedia page: https://en.wikipedia.org/wiki/Holodomor?wprov=sfla1

The Holodomor,[a] also known as the Ukrainian famine,[8][9][b] was a massive man-made famine in Soviet Ukraine from 1932 to 1933 that killed millions of Ukrainians. The Holodomor was part of the wider Soviet famine of 1930–1933 which affected the major grain-producing areas of the Soviet Union.

The Great Purge’s Wikipedia page (redirect from “Stalin’s purges"): https://en.wikipedia.org/wiki/Great_Purge?wprov=sfla1

The Great Purge or Great Terror (Russian: Большой террор, romanized: Bol’shoy terror), also known as the Year of ’37 (37-й год, Tridtsat’ sed’moy god) and the Yezhovshchina (ежовщина [(j)ɪˈʐofɕːɪnə], lit. ‘period of Yezhov’), was a political purge in the Soviet Union from 1936 to 1938. After the assassination of Sergei Kirov by Leonid Nikolaev in 1934, Joseph Stalin launched a series of show trials known as the Moscow trials to remove suspected dissenters from the Communist Party of the Soviet Union (especially those aligned with the Bolshevik party). The term “great purge” was popularized by historian Robert Conquest in his 1968 book, The Great Terror, whose title alluded to the French Revolution’s Reign of Terror.[9][10]

Katyn Massacre Wikipedia page: https://en.wikipedia.org/wiki/Katyn_massacre?wprov=sfla1

The Katyn massacre[a] was a series of mass executions of Poles carried out by the Soviet Union between April and May 1940. Though the killings also occurred in the NKVD prisons in Kalinin, Kharkiv and elsewhere, the massacre is named after the Katyn forest, where some of the mass graves were first discovered by Nazi German forces in 1943.[2] Nearly 22,000 Polish military and police officers, border guards, intelligentsia, and prisoners of war were executed by the NKVD (Soviet secret police), on Joseph Stalin’s orders.

Thought I’d do my best to provide context even though I don’t know as much about history cause I’m always excited when theres info in the comments ☺️