What is the belief behind the rain dance?

It was believed that it would help bring rain and end a drought. 

I knew the question right away considering I am Native American. In late August, when it is quite dry, especially in the Southwestern United States, Native American tribes used to do a rain dance. Many Native Americans still perform the ritual today, and it can be seen on several reservations in the United States. Men and women gathered together for a rain dance and wore special headdresses and clothing. The jewels used in the clothing, such as turquoise, had special significance, as well as the patterns of the clothing and the use of goat hair in the headdresses. These special clothes were worn every year for the rain dance and usually were stored the entire year for this purpose.

They had more africans americans than any other state