A few things, 1 souls are my gdp. 2 for every soul obtained I can make one skeleton or basic infantry or 1000 of them to revive my general when killed. 3 to get souls I have to KI11 enemy's, 1 soul per enemy ki11ed. Also any vehical's or whatever I will have to steal with enemy's.
If you want to bargain for peace you can either offer your dying people or vehicles that's it.