"More mapped" refers to the act of creating a more detailed or comprehensive map of a particular place or area. Some synonyms for this phrase include "better charted," "more thoroughly surveyed," "more accurately plotted," "more extensively mapped," and "more completely charted." These words can be useful for identifying the specific level of detail or comprehensiveness desired in a map. They can also be used to describe the level of knowledge or information that has been gathered about a location, and can be useful for planning, exploration, research, or other purposes. In short, by using synonyms for "more mapped," you can convey a more precise idea of what kind of mapping or surveying has been done on a particular area.