blond hair has been fashionable since the Ancient Greeks started coveting their neighbour's hair

... dyed hair was actually accepted as necessary for mourning when it was darkened. It could also be reddened, or made blond. This is the first indication of the tradition which was maintained by the Latin races & later by western society, that fair hair was more desirable than black and has connotations of innocence, superior race & sexual desirability. The blonds of ancient Greece were induced by a pomade of yellow flower petals, a potassium solution, or other coloured powders which veiled their hair with red, gold or silver. (p.29)

Writing in the second century, Apuleius expresses the Roman attitude when he says that the first thing he notices in a pretty woman is her hair, shining with golden light & glossy with spikenard lotion. Although he spares a glance for the dark haired woman, for him the truly attractive girl has blond hair. The Romans debased his view, dyeing their hair red or blond hair with with a soap from Germany which had originated in Gaul. Blond hair became the brand of a prostitute. The savages of the north ... sent this unguent to Rome ... (and) the fair hair of their women, which was made into ornate wigs ... (p.31)

Medieval women used blond & dark dyes, tho never red as that was the colour associated with witchcraft! Hair could also be lightened in the sun scroll down to pic of courtesan lightening her hair using hat without crown

Maggie Angeloglou - A history of makeup (London Studio Vista 1970)