The file holds 4x4 images which represent particular tiles or map objects. The game uses MCD[20-21] as a reference for which image to use: MCD + MCD * 256 + 35 (the +35 is due to the fact that the first 36 images (0-35) are for units and equipment as opposed to actual terrain. You'd expect an offset of +36 to be used, but no, they did go with +35).
454 images, 7,264 bytes in total.
550 images, 8,800 bytes in total. These sample images were taken using the land palette.