[10] The vast majority of the oblast's residents are ethnic Russians, with a small minority of Sakhalin Koreans.

Early maps of Sakhalin reflect the uncertainty of the age as to whether or not the land mass was attached to the Asian continent.

The fact that it is not connected was conclusively established by Mamiya Rinzō, who explored and mapped Sakhalin in 1809 and definitively recorded by Russian navigator Gennady Nevelskoy in 1849.

Ōtomari was supposedly established in 1679, and cartographers of the Matsumae domain mapped the island, and named it "Kita-Ezo".

Japan, concerned about Russian expansion in northeast Asia, unilaterally proclaimed sovereignty over the whole island in 1845.

In 1855, Russia and Japan signed the Treaty of Shimoda, which declared that both nationals could inhabit the island: Russians in the north, and Japanese in the south, without a clear boundary between.

The Soviet attack on South Sakhalin started on August 11, 1945, about a month before the Surrender of Japan in World War II.

It was not until the 113th Rifle Brigade and the 365th Independent Naval Infantry Rifle Battalion from Sovietskaya Gavan (Советская Гавань) landed on Tōrō (塔路), a seashore village of western Sakhalin on August 16 that the Soviets broke the Japanese defense line.

[14] In addition, because the treaty did not explicitly specify cession of the renounced areas to the Soviet Union, Japan officially considers South Sakhalin and northern Kuril Islands to be a territories of undetermined ownership and these areas are marked as No Man's Land with white color on Japanese maps, although Japan currently has a Consulate-General in Sakhalin's capital city of Yuzhno-Sakhalinsk, located on the renounced territory.

[15] On September 1, 1983, the Soviets downed Korean Air Lines Flight 007, carrying 269 occupants, including U.S.

Due to restrictions, the entire Sakhalin Oblast and its internal and territorial waters except for Yuzhno-Sakhalinsk are considered to be a border zone, which means that the freedom of movement for foreigners is dramatically restricted and any movement outside of Yuzhno-Sakhalinsk requires registration to the Federal Security Service (FSB) and the Border Guard.

The indigenous Ainu people have historically inhabited the southern part of Sakhalin Island, with only a small number remaining today.

The Ainu are not recognized as a separate ethnic group in the Russian census, making it difficult to estimate their total population.

There exists a notable minority of Sakhalin Koreans, who can trace their roots to the immigrants from the Gyeongsang and Jeolla provinces of Korea during the late 1930s and early 1940s, the latter half of the Japanese ruling era.

After the Red Army had seized control over southern Sakhalin at the end of WW2, all but a few Japanese there repatriated successfully, while most Koreans could not secure permission to depart either to Japan or their home towns in South Korea.

In addition, 37% of the population declares to be "spiritual but not religious", 15% is atheist, and 18.4% follows other religions or did not give an answer to the question.