Question

what do the isolated regions shows in yellow indicate

Answer 1

because they are uncultivatable land

Answer 2

The isolated regions in yellow denote the remote areas that lack all basic need.

For example, communication, transportations, etc. as these areas are quite away from the urban areas and hence the yellow colour on this region shows the uncultivated patches of land.

These lands do not have fertilizing and proper plowing methods.

Chances are also high that since people do not have knowledge on land cultivation, they are not ploughed properly.