Japanese: 関東 (Kantô), lit. "east of the check-points"
In ancient times, Kantô referred to the part of Japan east of the ancient capital area, in particular the part beyond the three 8th-century checkpoints out of Ômi province--the Suzuka checkpoint 鈴鹿関 in Ise province, the Fuwa (Sekigahara) checkpoint 不破の関 in Mino province, and the Arachi checkpoint 愛発関 in Echizen province, that is, the checkpoints along the Tôkaidô, Tôsandô 東山道 (Nakasendô), and the Hokurikudô highways.
Later, Kantô came to refer to the area of the large eastern plain (Kantô Plain) in which modern Tokyo is situated, and in particular the eight provinces in which the plain is situated, the provinces of Sagami, Musashi, Awa, Kazusa, Shimôsa, Hitachi, Kôzuke, and Shimotsuke.
The Kantô Plain was by far the greatest tract of agricultural land in Japan, and for a large part of the time after the Heian period rulers from the Kantô actually controlled the country. In the 10 century Taira no Masakado of Shimôsa attempted to proclaim himself "New Emperor." During the Kamakura Period (1185 -1333 ) the country was actually ruled from Kamakura in Sagami province. The Ashikaga shoguns were originally from Ashikaga in Shimotsuke, though they actually ruled from Kyoto. However, they established a Kantô Kanrei to control the Kantô. In the 16th century the Kantô was controlled by the Hôjô clan of Odawara in Sagami (the "later Hôjô"). they were destroyed by Toyotomi Hideyoshi in the Siege of Odawara in 1590, and the region was given to Tokugawa Ieyasu, who established his seat in Edo in Musashi. During the Edo Period (1603 -1867 ) the country was governed from the shogunal seat of Edo, and in the ninth month of 1868, at the time of the Meiji Restoration, the imperial capital was moved to Edo, which was renamed Tôkyô, "eastern capital".