Kaga was one of the Ancient Japanese Provinces. Located in what is now southern Ishikawa prefecture, it bordered Etchu and Hida to the east, Noto to the north, and Echizen to the southwest.
During the tumultuous Sengoku Era, Kaga was the birthplace of the fanatical and militant Ikko Ikki buddhist sect, which eventually grew to rule the province along with large swaths of central Japan.
After the Battle of Sekigahara in 1600, Tokugawa Ieyasu awarded Kaga to Maeda Toshinaga along with Noto and Etchu, giving the Maeda the huge fief worth more than 1,220,000 koku - the largest of the tozama domains, and the largest domain in Japan other than the Tokugawa's own domain. The Maeda family ruled Kaga until the abolishment of feudalism in 1871.
Kaga was also the name of a Japanese aircraft carrier, named after the ancient province, which served from 1926-1942, taking part in the attack on Pearl Harbor before being sunk in the Battle of Midway.