Kamakura (鎌倉市 Kamakura-shi) is a city in Kanagawa Prefecture, Japan, about 50 kilometres (31 miles) south-south-west of Tokyo. Although Kamakura proper is today rather small, it is often described in history books as a former de facto capital of Japan as the seat of the Shogunate and of the Regency during the Kamakura Period. Kamakura was designated as a city on November 3, 1939. The Kamakura shogunate era is called by historians the Kamakura period and, although its end is clearly set (Siege of Kamakura - 1333), its beginning is not. Different historians put Kamakura's beginning at a different point in time within a range that goes from the establishment of Yoritomo's first military government in Kamakura (1180) to his elevation to the rank of Sei-i Taishōgun (征夷大将軍) in 1192.