Why in ancient times did Indian children wear red bindis?

[i love guacomole!!]

Im asking this odd question because I had a dream I was an indian child, on my mothers
lap, looking in the mirror. I could see her long, tanned arm come around with bangles,
attempting to put a red bindi on my forhead.

I was being naughty, laughing and laughing, cause I wouldnt hold still to let her do this !!

Strange dream, anyway made me wonder why do children wear bindis? do they still?
and what part of india?

thanks