Chronology of Soviet secret police agencies in the context of "Heydar Aliyev"

The Gulag was a system of forced labor camps in the Soviet Union. The word Gulag originally referred only to the division of the Soviet secret police that was in charge of running the forced labor camps from the 1930s to the early 1950s during Joseph Stalin's rule, but in English literature the term is popularly used for the system of forced labor throughout the Soviet era. The abbreviation GULAG (ГУЛАГ) stands for "Glávnoye upravléniye ispravítel'no-trudovýkh lageréy " (Гла́вное управле́ние исправи́тельно-трудовы́х лагере́й or "Main Directorate of Correctional Labour Camps"), but the full official name of the agency changed several times.

The Gulag is recognized as a major instrument of political repression in the Soviet Union. The camps housed both ordinary criminals and political prisoners, a large number of whom were convicted by simplified procedures, such as NKVD troikas or other instruments of extrajudicial punishment. The agency was established in 1930 and initially was administered by the OGPU (1923–1934), later known as the NKVD (1934–1946) and the Ministry of Internal Affairs (MVD) in the final years.

The history of the Soviet Union between 1927 and 1953, commonly referred to as the Stalin Era or the Stalinist Era, covers the period in Soviet history from the establishment of Stalinism through victory in the Second World War and down to the death of Joseph Stalin in 1953. Stalin sought to destroy his enemies while transforming Soviet society with central planning, in particular through the forced collectivization of agriculture and rapid development of heavy industry. Stalin consolidated his power within the party and the state and fostered an extensive cult of personality. Soviet secret-police and the mass-mobilization of the Communist Party served as Stalin's major tools in molding Soviet society. Stalin's methods in achieving his goals, which included party purges, ethnic cleansings, political repression of the general population, and forced collectivization, led to millions of deaths: in Gulag labor camps and during famine.

World War II, known as "the Great Patriotic War" by Soviet historians, devastated much of the USSR, with about one out of every three World War II deaths representing a citizen of the Soviet Union. In the course of World War II, the Soviet Union's armies occupied Eastern Europe, where they established or supported Communist puppet governments. By 1949, the Cold War had started between the Western Bloc and the Eastern (Soviet) Bloc, with the Warsaw Pact (created 1955) pitched against NATO (created 1949) in Europe. After 1945, Stalin did not directly engage in any wars, continuing his totalitarian rule until his death in 1953.

NKVD troika or Special troika (Russian: особая тройка, romanized: osobaya troyka), in Soviet history, were special quasi-judicial proceedings composed of three officials from the security police (for much of the troikas' existence, the NKVD, hence the name) who issued sentences to people after simplified, speedy investigations and without a public trial. The three members acted as ad hoc judges. These commissions were employed as instruments of extrajudicial punishment introduced to supplement the Soviet legal system with a means for quick and secret execution or imprisonment. It began as an institution of the Cheka, then later became prominent again in the NKVD, when it was used during the Great Purge to execute many hundreds of thousands of Soviet citizens. Defendants in the Troika's proceeding were typically not entitled to legal aid or the presumption of innocence. Troika members employed common sense and socialist revolutionary principles to reach a verdict. Convictions usually did not include information about the actual incriminating evidence and basically contained only information about indictment and sentencing. The outcome of such trials was often predetermined before it even began due to targeted numbers of citizens to be executed or imprisoned in Gulag prison camps.

Troika means "a group of three" or "triad" in Russian.

Chekism (Russian: Чекизм) was the form of counterintelligence state widely present in the Soviet Union by which secret police, counterintelligence and internal security services (originally the Cheka, hence the name, but most famously the KGB) strongly controlled all spheres of society. Similar circumstances exist in some post-Soviet states, particularly Russia. The term encompasses both the ideological underpinnings justifying often arbitrary repression as well as the political situation where security service members occupy high-level political offices and a lack of civilian control over their activities (in extreme cases, the opposite). The term is sometimes also applied to other Eastern Bloc security services (long-serving East German security chief Erich Mielke was fond of calling himself a Chekist), and, presently, to the federal government of Russia under Vladimir Putin (himself a former KGB officer).

The name is derived from Cheka, the colloquial name of the first in the succession of Soviet secret police agencies. Officers of the succession of security agencies (Cheka, GPU, OGPU, NKVD, GUGB, NKGB, MGB, MVD, and, longest-lasting, the KGB), as well as their Russian successors, the Federal Security Service, are often referred to, both by themselves and by the broader public, as "Chekists".