Why didn't the Eighth Route Army and the Northeast Anti-Japanese Allied Forces establish anti-Japanese base areas in the Northeast?

What is said upstairs is part of it. There is also the practice of the Japanese army clearing the field, and the contradiction in the northeast is not prominent. 1937 after the lugouqiao incident, a large number of immigrants poured in from Shanhaiguan, about100000. It can be seen that after the outbreak of the all-round anti-Japanese war, the northeast is much stronger than the war-torn customs. In addition, the northeast is vast and sparsely populated, and the land problem is not acute. The above points have led to the fact that the anti-United front has no mass base, and it is difficult to establish base areas without mass base.