muramura, you sound as though you have got further than needing this but for anyone else:

Basic, about as minimal as you can get provincial campaign maps for rtw 1.5 and bi 1.6. One faction plus slave in descr_strat.txt. 200 pixels square map_regions.tga with a dozen regions, no ports so you don't need to worry about aligning coasts. Plain files for all other tga's:

http://uploaded.to/?id=kehwgm

No read me included if I have to describe where you put the files you're never going to be able to make map, so give up now!

To use this as base install and check it loads before modifying anything (they'll be under provincial campaigns as bi_base_map and rtw_base_map respectively).

Then re-size all the maps to the size you need following the sizes specified in Myrddraal's tutorial, also change the size listed in descr_terrain.txt to the size of your new map_regions.tga

When you re-size or alter the map_regions.tga make a copy of the little block of regions in the left hand corner first, blank out the area with one of the region colours, do your re-sizing / alteration and then paste the copy of the region block in somewhere you know it will be over land. Make sure any re-size option you use doesn't blend colours at edges of regions; 'nearest neighbour' and 'pixel re-size' work OK.

Once you are at correct size delete map.rwm and check it loads again.

Then start working on your map_heights.tga to define the coastline. Either just draw it in the blue and 'black' colours already used, or download satellite data etc. If you haven't put sea in corner where cities are you don't have to alter any other file to check that loads. If you have sea in corner copy and paste the block of regions so they are over land (and move army co-ordinates). Then delete map.rwm and check it loads again. If you get instant CTD with no map.rwm generated you may have too much sea...

Deal with map_heights first, then get regions neatened up / more regions added, before going on to worry about anything in map_ground_types, climates or features.