yeah.. i posted that map in China history forum along with this info:
When Manchus moved into China, Chosun people settled there since 1700's.
Problem rose when Qing wanted the land back in 1880's, but Chosun kept its people and administration there.
I've included a map of Chosun drawn by a French missionary below
in 1900's, Japan takes over diplomacy of Korea, and in 1909, signs the Gando(Jiandao) agreement with Qing, in which the region is given to Qing in return for some previledges in Manchuria, including the right to put down a railroad there.
after 1910, when Japan annexed Korea, independence movement moved into that region, because although it was now part of Qing, most of the people were Korean.
with Japan's surrender in 1945, all of its gains in territories and all the treaties it made is cancelled, including the 1909 Gando agreement.