Iga Province (伊賀国, Iga no kuni) was a province of Japan located in what is today part of western Mie Prefecture.[1] Its abbreviated name was Ishū (伊州). Iga is classified as one of the provinces of the Tōkaidō. Under the Engishiki classification system, Iga was ranked as an "inferior country" (下国gekoku) and a "near country" (近国kingoku).
Iga was bordered by Ise to the east and south, Ōmi to the north, Yamato to the west and south, and Yamashiro Province to the northwest. It roughly coincides with the modern municipalities of Iga and Nabari in Mie Prefecture as well as Yagyu in Nara Prefecture. Surrounded by mountains, historically, Iga Province was rather inaccessible due to extremely poor road conditions. However, the area is now relatively easy to access from nearby Nara and Kyoto, as well as the larger cities of Osaka and Nagoya.
Little is known of the subsequent history of the province during the Heian and Kamakura periods. However, by the middle of the Muromachi period, Iga became effectively independent from its nominal feudal rulers and established a confederacy, Iga Sokoku Ikki. During this period, Iga came to be known as a center for ninja activity. This serves that basis of its claim, along with Kōka in what is now Shiga Prefecture, to be one of the birthplaces of the ninja clans and ninjutsu.
In 1581, two years after a failed invasion led by his son, the warlord Oda Nobunaga launched a massive invasion of Iga, attacking from six directions with a force of 40,000 to 60,000 men which effectively destroyed the political power of the ninja (see the Tenshō Iga War).
Notable Edo-period people from Iga included the famous samurai Hattori Hanzō and the haiku poet Matsuo Bashō. Iga Ueno Castle was retained by Tsu Domain as a secondary administrative center for the western portion of the domain.
Iga was divided into 4 Districts (郡), which were further subdivided into 197 villages. The total assessed value of the province in terms of kokudaka was 110,843 koku.