The loincloth has been worn for thousands of years, but real underwear became popular in the Middle Ages.
The first underwear was worn thousands of years ago: the loincloth. It is not known who first tied a piece of fabric around the hips. It is known that the loincloth was used by cavemen, as outerwear but also as underwear, and afterwards also by the ancient Egyptians, Greeks and Romans.
It was not until the Middle Ages that people of high descent began to wear items of clothing under their clothing, and then others too.
The man's smock and the woman's shirt were loose pieces of clothing that were worn directly on the body. Men also wore large bib shorts, which initially looked like ordinary pants, but gradually became smaller and tighter, until around 1450 it had become a sort of loincloth.
In the 16th century women wore more and more a corset and an underskirt, and in the 19th century the underpants made their entrance into men and women.
Men's underpants were long and narrow, and women's underpants were loose and open in the crotch, and continued just below the knee. The French queen Catharina de 'Medici is said to have worn underpants in the 16th century.