Braies are a type of trouser worn by Celtic and Germanic tribes in antiquity

Classical antiquity

Classical antiquity is a broad term for a long period of cultural history centered on the Mediterranean Sea, comprising the interlocking civilizations of ancient Greece and ancient Rome, collectively known as the Greco-Roman world...

 and by Europeans subsequently into the Middle ages

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

. In the later middle ages they were used exclusively as undergarment

Undergarment

Undergarments or underwear are clothes worn under other clothes, often next to the skin. They keep outer garments from being soiled by bodily secretions and discharges, shape the body, and provide support for parts of it. In cold weather, long underwear is sometimes worn to provide additional...

s. Braies generally hung to the knees or mid-calf, resembling what are today called shorts

Shorts

Shorts are a bifurcated garment worn by both men and women over their pelvic area, circling the waist, and covering the upper part of the legs, sometimes extending down to or even below the knee, but not covering the entire length of the leg. They are called "shorts" because they are a shortened...

. They were made of leather, wool, or, in later years, cotton or linen

Linen

Linen is a textile made from the fibers of the flax plant, Linum usitatissimum. Linen is labor-intensive to manufacture, but when it is made into garments, it is valued for its exceptional coolness and freshness in hot weather....

. Adopted by the Romans as Braccae

Braccae

Braccae is the Latin term for trousers, and in this context is today used to refer to a style of pants, made from wool. The Romans encountered this style of clothing among peoples whom they called Galli...

.

Sources

• http://thescholarsgarret.com/artifact/braies/
• http://www.bumply.com/Medieval/braies01.html