I found something I found interesting, even if the translation needs to be smoothed out. It is called "Unique Marriage Styles of Tujia in Ancient Times." However, I don't think the styles are so unique.
It refers to "Group Marriage, Even Marriage, and Monogamy."
The Jade Emperor was very angry and made it be raining heavely. Most people died of the flood, but both brother Busuo and sister Yongnee escaped the disaster because they lived together in a sleeve. Later, Shiyitujie, the god of marriage, persuaded them to get married, and then a mass of flesh was born.Also...
She lived in a cave with two eagles every day. She was pregnant , and finally gave the birth of her son Tan Tianfei and her daughter Tan zhilan. Then, these two brother and sister got married and had eight children.Referring to "free" marriage...
In addition, it is also permitted for Tujia boy to get married with his adopted-sister. “Adopted -Sister Song” is recorded, “Adopted-sister, Orange tree’s leaf, Brother plays with adopted-sister at day, and sleep with adopted-sister at night.”
Ruled by the King Tusi during the Yuan, Ming and Qing Dynasty, monogamy was popular in Zhangjiajie region, but polygamy was also existed in rich family.
It goes on with some other marriage traditions. It is a reminder the idea that all marriages must be heterosexual, monogamous, and nonconsanguineous that is new.