Based on the file:
The Keepers of the Moon have a matriarchal society, with surnames passed down from mother to child—some since the First Astral Era
So miqo'te existed a very long time. Lol, maybe they were one of the 1st "human" race?

Additionally, prior to this data, all we knew was that miqo'te migrated from a southern continent into Eorzea and it was speculated that it was Meracydia due to it being the only southern continent we knew at the time. At least now this info pretty much confirms it.