In 1930, Imperial Japan extended from its main islands to control the Ryukyu Islands (Okinawa), southern Karafuto/Sakhalin Island, Chishima/Kuril Islands, Taiwan, the Caroline Islands, Palau, the Marianas Islands, the Marshall Islands, the Shandong Province of China, the Korean peninsula, and southern Manchuria.
Empire of Japan 1930; Wiki media Commons.
German territory 1914 ceded to Japan 1918; Wikimedia Commons.
Hello could I reference some of the information from this entry if I link back to you?
Certainly that would be fine.
I do believe Sakhalin was a not a Japanese colony. From 1907 it was a full part of Japan being a Japanese prefecture.
Sakhalin was first settled by Japanese fishermen along its southern coasts. In 1853 the first Russians entered the northern part. By an agreement of 1855, Russia and Japan shared control of the island, but in 1875 Russia acquired all Sakhalin in exchange for the Kurils. The island soon gained notoriety as a Russian penal colony. As a result of the Russo-Japanese War, Japan in 1905 (Treaty of Portsmouth) gained Sakhalin south of the 50th parallel and gave this part the Japanese name of Karafuto. After the Russian Revolution, the Japanese occupied all of Sakhalin, but they withdrew in 1924; in the following year White Russian forces were driven out of the north by Soviet troops. The Soviet Union regained the southern half of the island in 1945, at the end of World War II, together with the Kurils, and Sakhalin’s entire Japanese population eventually was repatriated.
https://www.britannica.com/place/Sakhalin-Island