What is fashion?
Fashions are things people own, wear or do, which, at that time, are supposed to be the "in" thing.
A thousand years ago, it was the fashion for Viking men to file their teeth into points - probably to look tough. Two hundred years ago, modesty was the fashion. People always wore hats when they went out in public (and often women wore them in the house too). Girls wore full-length dresses when they swam and boys wore neck to knee bathing suits!
Probably for as long as there have been people on the earth, there have been fashions and fads.