midway province
Archaic term for a province located partway along a major route from the capital, used in historical contexts. Compare 道の口 (entrance province) and 道の後 (farther province).
The provinces that were 道の中 served as important waypoints for travelers from the capital.
Compound of 道 (road, route) + の (possessive particle) + 中 (middle). The exact historical derivation is uncertain, but it follows the pattern of 道の口 and 道の後 for classifying provinces along ancient routes.