Why did the first child fall to death in the Yuan Dynasty?

The firstborn, as the name implies, is a child born with the firstborn. This custom is not common now, only in the Yuan Dynasty. This is a common practice. In the Yuan Dynasty, the Mongols took control of the China regime, and the Chief Executive, a native of Mongolia, had the right to have his first night. The newly-married woman had to wait on mongolia local's chief executive's house three nights ago (implicitly). In this humiliating oppression, the Han people formed a tragic means of struggle full of blood and tears-abortion of the first child. Every woman's first child must fall to death, so as to keep the purity of China's blood. Mongolia's policy of racial integration has also failed.