How and when were Russian oblasts put inside Ukraine?

The incorporation of Russian-speaking oblasts into 

Ukraine

's borders occurred primarily during the Soviet era, particularly in the aftermath of the 1917 Russian Revolution and during territorial transfers within the 

USSR

. This process was driven by a combination of historical shifts, population policies, and industrial development. 

The Soviet era and the Donbas region

Following the Russian Civil War (1917–1922), the Bolsheviks incorporated the Donbas (Donetsk and Luhansk oblasts) into the 

Ukrainian Soviet Socialist Republic (SSR)

. 

• 18th and 19th-century industrialization: Large-scale industrialization in the Donets Basin began in the 18th century after Russia annexed the territory from the Crimean Khanate.
• Influx of Russian workers: As Donbas became a key industrial center, it attracted an influx of workers from other parts of the Russian Empire, including many ethnic Russians.
• The Soviet period: Throughout the Soviet era, Moscow pursued policies of Russification, further increasing the Russian-speaking population in eastern Ukrainian cities, particularly after World War II. 

The transfer of Crimea in 1954

The 

Crimean Oblast

, which has a large Russian-speaking population, was administratively transferred from the Russian Soviet Federative Socialist Republic (RSFSR) to the Ukrainian SSR by decree in 1954. 

• Rationale for the transfer: Soviet officials stated the move was based on "the integral character of the economy, the territorial proximity and the close economic and cultural ties" between Crimea and Ukraine. It was also done to commemorate the 300th anniversary of Ukraine's unification with Russia.
• Legacy of the transfer: At the time, the transfer was largely symbolic within the Soviet Union. However, after the Soviet collapse, it became a major source of conflict between Ukraine and Russia. 

Broader historical factors

The Russian Empire's expansion and subsequent Soviet policies contributed to the demographic and linguistic makeup of many Ukrainian territories. 

• Russian imperial expansion: In the late 18th century, the Russian Empire annexed vast, sparsely populated lands in what is now southern Ukraine, known as Novorossiya ("New Russia"). Russian nobles were granted large tracts of land, which attracted a mix of new settlers, including many Russians.
• Soviet border adjustments: During the early years of the Soviet Union, Ukrainian borders were established to include 
  Novorossiya
   and other areas with significant Russian populations. This was intended to gain support from the local population.
• Post-WWII resettlement: After World War II and the deportation of Crimean Tatars, the Crimean Peninsula was resettled by new migrants, many of whom were ethnic Russians. 

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Ukraine

 formally became an independent country on August 24, 1991, following the collapse of the Soviet Union. On that date, the Ukrainian parliament (Verkhovna Rada) approved the Act of Declaration of Independence of Ukraine. 

Key events confirming Ukraine's independence include:

• December 1, 1991: A nationwide referendum overwhelmingly confirmed the declaration of independence, with over 90% of voters supporting it.
• December 25, 1991: The United States officially recognized Ukraine's independence. 

While 1991 marks the modern state's founding, Ukraine has a long and complex history that includes earlier periods of statehood. For example, a Ukrainian People's Republic was formed in 1918 following the Russian Revolution, but its independence was short-lived.