What does "crossing the Kanto" mean? What is the reason?

"Eastward" means that people in Shanhaiguan pass through Shanhaiguan to make a living or settle in the east of Shanhaiguan. Because the specific direction of Shanhaiguan is east-west, not north-south, it is called Kanto.

After the Qing government was established, it believed that the Northeast was their birthplace, and Han people in the mainland were not allowed to reclaim land casually. Gradually build a "wall" of more than a thousand miles with wicker, so that Manchu people can enter the customs, but Han people can't get out. Over time, North China is overcrowded and Northeast China is sparsely populated. Thus, from the middle of19th century until the founding of New China, a large number of people from the Central Plains (mainly from Hebei and Shandong) began to "break through" and make a living in the Northeast. In other words, "going east" is a great population migration.

Nowadays, there are Shandong dialect, Hebei dialect and Manchu characteristics in the northeast dialect, which is so "hot".