noun, used as a suffix
north of ...; ... and northward
Suffix attached to a place name to indicate the area north of that place, or the region including and to the north of it.
東京以北の地域では雪が降りやすい。
In areas north of Tokyo, snow tends to fall easily.
この列車は仙台以北には行きません。
This train does not go north of Sendai.
Compound of 以 (i, 'from') and 北 (hoku, 'north'). The reading いほく is a regular on'yomi combination.