The bandon (Greek: βάνδον) was the basic military and administrative territorial entity of the middle Byzantine Empire. Its name, like the Latin bandus and bandum ("ensign, banner"), had a Germanic origin. It derived from the Gothic bandwō, which is the witness of foreign influence in the army at the time this type of unit evolved. The term was used already in the 6th century, mentioned by Procopius, as a term for a battle standard, and soon came to be applied to the unit bearing such a standard itself. Since the time of ruling Nikephoros I (802–811) it was the name for a subdistrict of the Byzantine thema.
In the Byzantine army of the 8th–11th centuries, the bandon formed the basic unit, with five to seven banda forming a tourma, the major subdivision of a thema, a combined military-civilian province. Each bandon was commanded by a komes ("count"), with infantry banda 200–400 strong and cavalry banda 50–100 strong. It is considered that the bandon in the Tactica (9th century) previously in the Strategikon (6th century) was alternatively written as tagma or arithmos.
Infantry banda was formed by sixteen lochaghiai, each with sixteen man, commanded by an officer lochaghos (file leader), which was assisted by dekarchos (leader of ten), pentarchos (leader of five), tetrarchos (leader of four), and ouraghos (file closer). Each four lochaghiai formed an allaghion (winglet), and around three-quarters of the men were spearmen skutaoi and one-quarter were archers. At the time the Strategikon was written, the cavalry banda was subdivied into three hekatontarchia, each commaned by a hekatontarchos with a senior second-in-command illarches.
Since the time of ruling Leo VI the Wise (886–912), the hekatontarchia disappeared and the bandon was divided into six allaghia (probably commanded by pentekontarchai), and each pair was still commanded by a hekatontarchos or kentarchos. Each of six allaghia had fifty men, organized in five dekarchiai of ten men each. All four officers (dekarchos, pentarchos, tetrarchos, ouraghos) were lancers.
At the beginning of the 10th century the infantry unit consisted of 256 men (16x16), and cavalry unit of 300 men (6x50), but the manuals indicate that the unit strength in fact varied between 200 and 400 men. The work Praecepta Militaria by Nikephoros II Phokas (963–969) indicates that the cavalry bandon was only 50 strong. Unlike other middle Byzantine administrative and military terms, the bandon survived well into the late Byzantine period, and remained the basic territorial unit of the Empire of Trebizond until its fall.