@strijder20:
-My advice is to send your starting Galley over to India and trade for Ivory. Maintain good relations with China and cave to their demands;
don't worry, they'll be dying soon enough. When the Mongolians come; they'll usually conquer China,
from Corea, send in a stack of War Elephants+Samurais+Cats and start razing badly placed cities and routing Mongolian armies.
When China respawns, they will either be:
-Weak and voluntarily vassalize to you.
-Weak and easily conquerable since they'll only have 2-3 cities tops from razing all the non-essential cities.
If they are beating back the Mongols, then what you'll need to do is assist the Mongols by invading the eastern seaboard simultaneously.
Pay attention and leave an Explorer or some other unit in the Chinese capital to monitor progress.
-I don't think there's anything special about natural Japanese stability after playing them semi-frequently. (Rhye's is still a Japanophile though).
However, AI Japan never collapses, which is absurd.
There were certainly periods of disunity and turmoil in Japan throughout its history.
The Genpei Wars and the Sengoku period are perhaps the two best examples.
Not that it has a powerful bearing on gameplay, but it's something to be left considered.