This is a quick and easy fix (the hardest part was actually figuring out the map coordinates) for the issue with the mines in the Dahyu Daha province - the mine building is there from the start, it just doesn't produce anything. This sorta crimps the Pahlavas' style in the early game, but fear ye not - help is here.

Anyway, do the following:
1) delete "map.rwm" from the "\EB\Data\world\maps\base" folder.

2) backup "\EB\Data\world\maps\base\DESCR_REGIONS.TXT" and "\EB\Data\world\maps\campaign\imperial_campaign\descr_strat.txt".

3) open "DESCR_REGIONS.TXT" and search for the Dahyu_Daha entry - it should look like this:
Code:
Dahyu_Daha
       Nisa
       parthia
       Parni
       192 137 84
       hides, textiles, camels, nomad, pahlavahome, EA, A, n1, y2, n4, y8
       5
       1
...and add "gold," to the list of resources, so it looks something like this:
Code:
Dahyu_Daha
       Nisa
       parthia
       Parni
       192 137 84
       gold, hides, textiles, camels, nomad, pahlavahome, EA, A, n1, y2, n4, y8
       5
       1
Save the file, we're done here.

4) open "descr_strat.txt" and search for the word "gold" - you should now be at a long list, part of which looks like this:
Code:
resource   incense,   199,   93
resource   incense,   180,   75
resource   gold,   20,   140
resource   gold,   140,   120
Now add to the list the line "resource gold, 283, 158", so you get something like this:
Code:
resource   incense,   199,   93
resource   incense,   180,   75
resource   gold,   20,   140
resource   gold,    283,   158
resource   gold,   140,   120
Save the file.

The next time you start a new campaign, there should be a pretty little mine churning out money at the tip of that mountain ridge to the west of the settlement of Nisa, and the Pahlava are a that much happier bunch of bowlegged nomadic conquerors with silly moustaches.

Alas, like AFAIK all modifications to the "\world\maps\" folders, this doesn't do a thing to ongoing campaigns. Can't have everything.