Hey. When given the option to choose the map, pick the Middle one. Riverside. When you completed the mission Garrin will be available as a Zen Master for Kenji. Why him? He has the ability to summon horses. Some maps in the game will have this resource but the Player is not allowed to build stables. With Garrin this will negate the effect. Don't use the horses for your troops. Give 2 to the peasants working the padi fields & 1 for the water gatherer. Therefore you can minimize the usage of peasants as gatherers. They will quickly replenish your resource pool & you will be able to free up peasants for troops.

This works when Kenji plays as the Dragon Clan only. Have fun & good luck.