The centre, or most populous part of a region defined by geographical or non-geographical criteria
Journalists use heartland or heartlands to refer to the area or region where a particular set of activities or beliefs is most significant. his six-day bus tour around the industrial heartland of America
the central region of a country or continent; especially a region that is important to a country or to a culture
The most central area of a country or continent can be referred to as its heartland or heartlands. For many, the essence of French living is to be found in the rural heartlands