Ever played Genghis Khan IV? It is in the similiar fashion as the mod you propose, except without the MTW battle engine. The campaign map covers the enitre Euroasian continent, from Britain to Japan, as well as North Africa. It is produced by Koei.
There are four campaign eras:

1. 1189, Mongol faction with Genghis Khan, faction with Jamuka, faction with Wang Khan, Karakhitai Kingdom, Xi Xia Kingdom, Jin Empire, Song Empire, Koryo, Annam, Ghurids, 2 Japanese Shogunates, Khwaranian Shah, Ayyubids, Byzantines, Princes of Kiev, HRE, France, England, Scandanvia, Hungary, and Sicily, etc

2 1129, Mongol Empire with Ogedei Khan (along with Batu Khan, Hulegu, Tulei, Subudei, etc), dying Jin Empire, Song Empire, Koryo, Annam, Sultanate of Dehli, Japanese Shogunate, Ayyubids, Byzantines, Novograds, HRE, France, England, Scandanvia, Hungary, Milan, and Venice, etc

3. 1270, with Kublai Khan's Yuan Dynasty, Kaidu's Ogedei Khanate, Golden Horde, Abaqua's Ilkhanate, Chagatai Khanate, Koryo, dying Song Empire, Annam, Sultanate of Dehli, Japanese Shogunate, Mamlukes, Byzantines, Novograds, HRE, France, England, Scandanvia, Hungary, Milan, and Venice, etc

4. 1371, with Tamerlane's Empire in Samarkand, Ming Empire in China, Koryo/Choson, Japanese Shogunate, Annam, Sultanate of Delhi, Mamlukes, Byzantines, Ottomans, Golden Horde, Russians, Spanish, HRE, France, England, Hungary, Milan, Venice, etc