Peter is instructing the “wives” of Pontus, Galatia, etc., in the days of the Roman Empire to dress themselves with a particular sort of conduct. But what he is asking is not unique to their time or place. They need to conduct themselves in this fashion because this is how holy women of the past (and so in other cultures) adorned themselves. The principle is not bound to time or place.
5 For this is how the holy women who hoped in God used to adorn themselves, by submitting to their own husbands,