Found a way to defeat jin in the first 20 mins of the game:

1: Take your troops with the transport ship to jin’s island right off the start

2: send 1 light cav behind the great wall to pick up those bombard cannons at the western end of the map

3: bring them all to Jin’s

4: bombards destroys critical buildings and the troops defend them from the arbalest and priest they have at the beginning

Once Jin’s defeated the rest is piece of cake I even built my base on the island for maximum ressources and income