In pre-modern times, women either weren’t allowed to ride horses or they had to ride side-saddle. Horses were usually for men
How did it come to be that horses are now seen as a womanly interest, to the point that some action movies need to put beards on women for scenes where characters are on horseback?
More can always be said, but this older answer might be of interest for you, written by /u/malthus1.