Although natives of Naishou Province tend to refer to the entirety of the land between the Taru Mountains and the Kawa Forest as the Nobu Valley, technically the valley is only the central part of the province that that drains into the Itochu River. Small lakes, streams, and rivers (none navigable for very long, if at all) dot the valley, all feeding the Itochu. The soil, as in most river basins, is exceptional, and the best farmland in the province is here. The majority of the province's population lives here in many dozen dozen villages. Most tend to exchange goods with the other villages in their area and pool resources for shrines and temples. Each village in a given network will typically have 1 or 2 unique or specialty services (an inn, a teahouse, a smithy, etc.) and these networks are typically closed economic systems. It is not rare to find a samurai living in 1 of these villages, but it isn't common, either.
The valley is the Itochu River's drainage basin. At turns it is plains, rolling hills, and scattered forests, all dotted with lakes, streams, and small rivers that feed into the Itochu.
Abundant, exceptional farmland and a bounty of fish from the valley's waterways.