A small mountain-ringed province located on the main island of Honshuu, famous for its ninja clans and considered one of the birthplaces of the ninja arts. Its distance from major trade routes, relative inaccessibility, and defensibility made it unattractive to invasion from outside forces. By the mid-1600s the local warrior clans had banded together to keep the province independent, forming a league known as the "League of all Commons of Iga" (伊賀惣国一揆 Iga Soukoku Ikki).

However, Oda Nobunaga invaded the province with an overwhelming force of 40,000 - 60,000 troops in 1581, two years after a failed invasion by his son Oda Nobukatsu, ruthlessly slaughtering many of its inhabitants, thus putting an end to the independence of the Iga League.