test 3a 00 48 00 04 00 19 19
amer 3a 00 48 00 04 00 19 03
big  3a 00 48 00 04 00 19 19

this is for a map of size 56 (58) by 70 (72), which appears to be the only size the
map maker wil create

So:
3a 00 48 00 04 00 
is apparently always at the start of a map.

I believe this would mean:

co ?? ro ?? ?? ??

co = columns 
ro = rows

The actual number of tiles in each row or column appears to be two less than the number shown




0x6 to 0x1055 is one section
0x6 to 0x40 appears to all be 0x19s
0x101b to 0x1055 appears to all be 0x19s

each row is one sequence of 55 bytes, with two 0x19 bytes in between rows

0x00 = tundra
0x01 = desert
0x02 = plains
0x03 = prarie
0x04 = grassland
0x05 = savannah
0x06 = marsh
0x07 = swamp
0x08 = boreal forest
0x09 = scrub forest
0x0a = mixed forest
0x0b = broadleaf forest
0x0c = conifer forest
0x0d = tropical forest
0x0e = wetland forest
0x0f = rain forest
0x18 = arctic
0x19 = ocean
0x1a = sea lane
+0xc0 = major river
+0x40 = minor river
+0xa0 = mountain
+0x20 = hill

0x1056 to 0x20e0 is one section