The idea of core and hinterland has been popularised by Christine Counsell, a history specialist, to help choose what to study when we can’t learn all there is to know.  Core means the main content of the areas of study; the most fundamental parts and perhaps the things you’ll be tested on later. Hinterland is the vast array of material that lies beyond our core. We don’t have time to study it in detail but it helps to know what’s there so the core makes more sense.