Bear in mind that Chinese cultural groups are far from uniform. For instance, Tibetan-speaking "Mongolians" can be found in Henan, while Tibetan-speaking "Islamic" peoples can be found elsewhere. (details see Stuart, Banmadorji, Huangchojia, 1995) 

Each culture has its own views of social relationships.  The wedding highlights these aspects.  From the wedding activities we can learn about their social values.  For many Chinese, the wedding is a social event between two families.  As for Jiarong Tibetans in Szechuan, it is a social event between two communities. 

The most interesting aspect about this wedding custom is that the newly-wed couple can not spend their wedding night together.  After the wedding ceremony, the bride is always accompanied by her chaperone, even staying overnight with the groom's families. The next day, they return to the brides' family and stay at their house for a couple of days, or even longer.  Later after returning to the groom's home, the couple can finally be truly united. 

Source: Stuart, K, Banmadorji, and Huangchojia. (1995).  Mountain gods and trance mediums: A Qinghai Tibetan summer festival: Asian folklore studies.  54, 1995: 219-237. 
Shan, Z. E. (1997) "Huen Li Qi Qu" [An interesting wedding]: Cultural Dialogue. 1997, 1.