Is the back yin or yang?

The yin and yang of the human body, the back is yang and the abdomen is yin. While women have yin in the back and yang in the abdomen.

In ancient patriarchal society, men were defined as yang and women as yin. Then the man's back is the yang in the yang, and the abdomen is the yin in the yang, and it is the yin. And women themselves are yin, the back is yin in yin, and the abdomen is yang in yin, not yang.