Early Romans did not wear pants. Both men and women wore beautiful, draped garments such as the toga or the stola, a long gown that hung nearly to the feet. Leg coverings were seen as crude items, worn by the barbarians who lived beyond the borders of Roman civilization or as the leg protection of the very poor. Yet as the soldiers of the Roman Empire (27 B.C.E. –476 C.E. ) began to venture further to distant lands, they began to understand why the peoples of Gaul, present-day France, and Britain wore long pants known as braccae. Simply put, these barbarian garments were needed to keep warm. Other cultures, such as those in Persia, modern-day Iran, and the Middle East, wore pants to protect the legs.
One of two pairs of trousers that the Romans borrowed from conquered peoples—the other were called feminalia—braccae were crude woolen trousers that were secured at the waist with a leather tie and often tied at the ankles as well. The word "braccae" is believed to be the root of the modern word for breeches. Unlike the feminalia, braccae were loose fitting. Those that were modeled after trousers from the warmer Middle East may have been made of cotton or silk. Braccae never came into common use in Rome, the capital of the empire, and some emperors forbade them to be worn in the city. In fact, they seemed so strange and foreign that one of the ways that Roman sculptors and painters identified foreigners was to depict them wearing braccae.
Yates, James. "Bracae." Smith's Dictionary: Articles on Clothing and Adornment. http://www.ukans.edu/history/index/europe/ancient_rome/E/Roman/Texts/secondary/SMIGRA*/Bracae.html (accessed on July 24, 2003).
[ See also Volume 1, Ancient Rome: Feminalia ]