The zip file in this download is named 'Chengdu-AXDIII-OP.zip' and contains a map file named 'Chengdu-AXDIII-OP.map'. After downloading the zip file, unzip the map into the folder: \SIERRA\EmperorRotMK\Cities. That will make it available for selection in Open play, or for viewing in the editor.
This is a modified version of the Chengdu map from the "A Xia's Diary III" custom campaign. It is 'enormous' in size, and has a temperate climate. A list of the modifications that are included on it is as follows:
1. Salt deposits were added to the northwest edge of the map.