Ahistorical story tells of a northward voyage taken by a group of people. the suffux-ward implies

The suffix "-ward" implies the direction being taken by the group of people. In this case, northward means the voyage was undertaken towards the north. This suffix is often used with other directional points on the compass such as south, east, and west (as well as their combinations). It may also be used with other directional terms like upward, backward, outward, leeward, and more.