How did the Kwantung Army come to the Northeast?

1900 after Eight-Nation Alliance entered Beijing, Russia took the opportunity to send troops to occupy the whole northeast of China and incorporated the northeast into Russian territory.

At that time, the Qing government could not defeat Russia in the war, and Russia was unreasonable in the negotiations with Russia, so it had to ask Japan for help. At the request of China government, Japan went to war with Russia in 1904, and sent more than 300,000 Japanese troops to the northeast of China to fight the Russian army. At the cost of 140000 Japanese soldiers' lives, Japan defeated the Russian army, recaptured the Northeast from Russia and returned it to China.

In order to thank Japan for its help, China decided to put Manchuria Railway and its areas along the line, as well as Lushun and Dalian under Japanese management, allowing Japanese immigrants to reclaim land in the northeast and allowing Japanese troops to station troops in the northeast to prevent Russian aggression again. This is why the Japanese Kwantung Army came to the northeast of China. In fact, by the time of the September 18th Incident, the Kwantung Army had been stationed in the Northeast for more than 20 years.