I really don't understand what is so difficult -
Using a globe, the size of the active map would be the simplest method of removing desolate land from the map. New accounts that increase the size of the map - ummm increase the size of the globe?
As for trading partners - from the Elvenar Wiki
"In addition, all bordering cities of that Province will also become "discovered".
As a result, trading with those neighbors becomes cheaper and you will be able to start giving them
Neighborly Help."
Interestingly, the expansion & Rune are defined as
"By completing Provinces you can also get
additional rewards: Province Expansions and/or Rune Shards."
The implication by both position of the Wiki and the language is neighborly help & trading partners are the primary purpose of the Map and the Expansion & Rune are rewards for the effort of completing the provinces.
The purpose, which you pay for with troops and/or resources, for completing provinces is to acquire neighbors for Neighborly Help & Trading Partners.
I point this out for those that insist the map is for expansions not neighbors - clearly that is not the accurate perspective, which makes sense considering expansions can be acquired through research, unlike neighbors, which can only be acquired by completing provinces on the map. Also, Runes can be acquired through Tournaments and Ancient Wonder chests won by helping other players, unlike neighbors, which can only be acquired through the map.
No doubt some are thinking - trading partners & neighborly help is also obtained through Fellowships; the difference is Fellowships are an option not essential to game progression - it is advantageous but not required.