Belts and girdles are fairly common in illustrations and portraiture from the Middle Ages and Renaissance, so this webpage instead focuses on extant examples of various styles. For more on belts and belt-buckles, plenty of links.
Early Middle Ages-- Alb—A liturgical vestment of the Catholic Church. A long white tunic with narrow sleeves and a slit for the head, tied with a belt. The name derived from the Roman tunica alba (white tunic).
Lower garment made in half of century, Walcher, Werke der Volkunst I, 1923 Check source book for more information! Does Lower Garment mean Underwear? The German word for smock might translate as lower garment.