Tips to Beat Nanman
Personally I’ll leave the Nanman untouched until late game. Let them bicker among themselves or engage with Liu Yan. If they declare war on you, just play it defensive. Nanman is really hard to invade as han force.
But say you want to clean them anyway. Against Nanman, this is hot stuff but I abandon artilerry and cavalry, focus on melee and some crossbowmen mixed with repeating crossbowmen. They might be weak to fire, but using fire on Nanman jungle is just as destructive to you if you’re not careful. Cavalry lose their speed in Nanman jungle.
So just use ji infantry as frontline, since Nanman warrior use axe that break shield and their slingers need to flank anyways to get clear shot once you’re engaged, Zhanmajian as flanking force. If you’re broke, axe guy works too replaceing Zhanmajian.
If you’re insistent on using fire, replace repating crossbowmen with juggernauts and crossbowmen with archers. Just make sure you don’t burn your side of the forest or better yet, fight in the clearings, but leave some expendables in the forest for vision. Burn the expandables along with the Nanman with the juggernaut at worst case, best case you move juggernaut to flanking position and burn the Nanman.