Peter appeals to history as he continues his discussion of submission within marriage. Take a look at his example in 1 Peter 3:5-6.
Peter looks to the past, and to the women listed in the Scriptures as an example of how submission is to play out in the realm of marriage.
While the NIV makes this text easy to read, it actually doesn’t translate it the most clearly. Other translations bring out the structure of Peter’s statement here much better. For example, the NRSV states it like this:
The holy women who hoped in God used to adorn themselves by accepting the authority of their husbands.
That allows us to see the structure of Peter’s statement, and not just our own adjusted interpretation. The main point behind all of this is the attitude of submission. And what Peter is emphasizing in this passage is the idea of adornment. Many of the women that came from pagan backgrounds were accustomed to much outward adornment. Peter says that the inner adornment, the attitude of the heart, is much more to be preferred.