Regarding The Tain

I found The Tain to be my favorite of the mythologies. Perhaps because I found it a quick read, or maybe the prevalence of Celtic influence in pop-culture; being the heavy metal geek I am one of the recent albums getting play on my morning commute is by a band Suidakra. Crógacht actually details Cuchulainn's travel to the Isle of Skye where he learned many of his warrior traits from a warrior woman named Scathach.

Consider that Cuchulainn learned much of his fighting craft from a female, then consider the prominent role that Queen Medb has in The Tain. Not only did she use womanly guile and blatant sexuality to achieve her ambitions, but is a fierce warrior in her own right and unafraid of combat.

It's obvious that women are given a powerful role in Celtic Society that far surpasses their roles in Greek and Hindu mythology. My question is why do you think this was? I'm curious as to why what theories there are about how a matriarch-driven society evolved during a time when so much of the world was dominated by men.