How old the girls first menstrual period of about When First Menstruation in girls?

How old the girls first menstrual period and When First Menstruation in young girls so what First steps of Menstrual cycle?Menstruation is a accustomed action accomplished by women. Back are usually girls 'coming months' the aboriginal time? Is there an ideal age? What if her age had not yet active the visitor's accession monthly?Each babe has aboriginal aeon of time different. Something happened