How did people back at the dawn of the bronze age get their fire hot enough to convert raw materials into bron?

If clay is mixed with straw, made into a dome, and fired by building a fire inside, the straw burns out and leaves and insulating surface that retains heat better. By building a charcoal fire with hide bellows feeding air to the fire pit by clay tubes shaped in the ground, the inside of the dome can be made very hot and materials can be melted in clay pots.