Women on their Moon
These ceremonies are for life. The continuance of life, so the people may live. A woman during here menstrual cycle is incredibly powerful, and it's the one time a woman cannot procreate. It is a cleansing time and life cannot be carried within the woman's body.
Women create Nations, they bleed every month (unless they are past their time or medical reasons) and there fore do not need to Sundance. There are ceremonies that are just for Women and Sundance is a ceremony that was meant for men. However if it were not for the women this ceremony would have been lost during the dark days. When indigenous ways of life were outlawed. Women do not need to pierce as they bleed every month and give birth and that is their sacrifice.
Anyway since the ceremonies are for life and a woman is in such great power but not for life this is why women on their monthly time are not allowed around the ceremonies. It has nothing to do with being clean or any such misconception. It is a Very Powerful time and the most powerful Medicine Man could not stand up to it.
Traditionally Moon Lodges were Never found near ceremony. True moon lodges were found just outside the village, and the ceremonies again were even in a different place. Today at some places moon lodges are found here and there around ceremony but that's not true where we go.