The Dii (also Dioi ) were an independent Thracian tribe, swordsmen, who lived among the foothills of Mount Rhodope in Thrace. They often joined the ranks of organized armies as mercenaries or volunteers. Thucydides declared that they were the most warlike infantry in Sitalkes' army.
Though usually described as swordsmen, they defeated a Theban cavalry by using peltast tactics, so they were certainly skilled in other areas of warfare as well.
See also: Bessi.
