Easily obtain funds by equipping the "Steal" feature onto your weapon using "Special" when you go into the forge. First, find a city that has a forge while making sure you have enough money and the correct type of gems to equip onto your weapon. When "Steal" is equipped onto your weapon, use it to steal gold from your enemies, lieutenants, guard captains, normal enemies, and generals. During battle, wait until you get a horde of enemies surrounding you to get plenty of gold. Repeat as many times as desired when you invade other countries.