usually between the ages of 10 and 14, but everyone is different. some girls start at age 9, others at 15. i read a story about a girl whose period didn't start until she was seventeen. mine started when i was eleven. if you start a little earlier or later, do not worry about it :)
Nothing specific. Just the beginning of periods.
no i had mine at 11
an eon
Possibly.
a drought.
144 mya
20 mins
there is actually no way you can start your period faster
1900 to 150 B.C.
The fall of Rome in 410AD
yes nine year olds can get their period
89 years