I circled this place on the map. Where is it now? Was it once China's?

Sakhalin Island, also known as sakhalin island, now belongs to Russian territory and belonged to China before the late Qing Dynasty.

1858 and 1860, Russia forced the Qing government to cede Sakhalin Island through treaties such as the Love-faint Treaty and the Sino-Russian Beijing Treaty. 1905, Japan acquired the area south of 50 north latitude of Sakhalin Island through the Treaty of Portsmouth. From 1905 and 19 18 to 1925, Sakhalin Island was ruled by Japan. 1945, the Soviet union launched the August storm and occupied the whole territory of Sakhalin Island. 1947, Sakhalin Island was established as a national management of Sakhalin Island. 195 1 year, Japan gave up the sovereignty of Nanhuatai in the San Francisco Peace Treaty, but it was not handed over, so the southern part of the island (south of 50 north latitude) is still a blank area in the map of Japan. Sakhalin Island is completely controlled by Russia.