Kawanakajima, which literally means "island between the rivers," is a vast triangular plain south of the city of Nagano, Japan, formed by the Sai River to the north, the Chikuma River river to the south, and a mountain range to the West.
During Japan's tumultuous Sengoku Era, the plain formed a sort of no-man's land between the domains of the two great daimyo lords Takeda Shingen and Uesugi Kenshin. In twelve years, from 1553 to 1564, the two warlords fought five battles at Kawanakajima, none of which resulted in a conclusive victory for either side. When people refer to the Battle of Kawanakajima, they usually thinking of the fourth and most famous battle in 1561, which involved almost 40,000 samurai and was one of the bloodiest battles in Japanese history.
Today Kawanakajima is a popular tourist destination. The Hachimanpara Battle Park is located near the spot where Shingen and Kenshin supposedly met each other in single combat at the climax of the fourth battle, and features a famous bronze statute of the two lords facing off, Kenshin on horseback, attacking with his sword, and Shingen, caught by surprise, still seated and defending himself only with a metal war fan. Nearby is the interesting Nagano City Museum, which has extensive exhibits on the battles and the history of the Nagano plain in general.
Also worth seeing is the nearby village of Matsushiro, which was the castle town of the Sanada family, and played an important role in the fourth battle. A short walk or bus ride away from the Battle Park, it features the castle remains and several preserved samurai houses.
To get to the Kawanakajima battlefield area, take a bus from the Nagano train station to the Hachimanpara or Matsuhiro bus stop.