There was a land where everyone lived in caves. The caves kept them safe from the wild creatures outside, but they were dark and no one could see anything inside. When the people lit torches so they would have light smoke would fill the caverns and everyone would cough all the time and their eyes would be watery and they couldn't see very well.
One day a group of people said "It's dark and smokey in here and we always feel sick, we're going to go live outside where the air is clean." So the group went outside and when they were done hunting and gathering they didn't go back inside the cave. When the people inside the cave came out the next morning, several of the people who had stayed outside were missing. "Some of them got lost, and we haven't seen them since then, and some got eaten by a bear, but the air is fresh and clear, and the rest of us feel much better!"
After another few days though, there was no one left outside, most had disapeared or been eaten, and a few had finally given up and moved back into the caves. A few years later another group tried the same thing, and again within a week the few survivors were back inside the caves.
Again in a few years a third group decided to go outside. After the first night out and several people had been eaten by some lions, one of them noticed a nearby hill. "If we moved to the top of the hill, we could post guards who could see any animals approaching and we'd be safe" So the people moved to the top of the hill and they were much safer, and soon a city was growing atop the hill. The people who still lived in the caves would look up at the city on the hill, and were very impressed with it's magnificence.
At first the city-people and the cave-people got along. But after awhile, as the city grew, the city-people began to feel superior. They had farms on the hill, and herds of goats they would take out to pasture by day and would bring back to the hill by night. Soon they had a surplus of food and some of the city-people became artisans and the city became richer as it grew. The cave-people still lived in caves and still choked on smoke from the torches and still spent most of their time hunting and gathering.
The city-people paid some of the cave-people to come work in their city, so that the city-people did not have to perform hard labor or menial tasks themselves. At first the cave-people were glad for the opportunity, but then they grew jealous.
"Teach us how to build our own cities," they asked.
"We shall not teach you because you are too primitive."
"Why are we primitive?"
"Because you live in caves instead of in cities."
The city-people built new cities on all the hills they could find. The cave-people tried to build their own cities, but all the hills were taken, and they didn't have much success.
The city-people laughed at the failure of the cave-people, and felt even more superior. They treated their cave-people servents worse and worse.
The cave-people became angry with the city-people, and the cave-people who worked in the city demanded that they be treated better and share in teh wealth, and when they were refuesed, they tried to fight the city-people. The city-people became angry in turn, and forced all the cave-people out of the city. The city people had to do their own work again, but at least now they were safe.
The cave-people started attacking the goat-herds, and the city-people were not able to protect all the goats at once, so they had to give up the goats, and only sent out hunting parties who could defend themselves and bring back meat for the city. At first everyone was hungry, so many of the artisans had to become hunters to make sure there was enough food.
The cave-people could not fight the hunting parties, so they started throwing rocks up at the city on the hill. The city-people were worried, so they built a wall to keep out the rocks. They no longer had the view from the top of the hill, but at least they were safe.
Then the cave-people started throwing the rocks up over the walls, and the city-people became scared again. They debated for awhile, but eventually decided that they had to build a roof over the city. They built a great dome over the entire city, and it was very impressive to those who looked up at the city from below. However inside the farms died because there was no light, and they had to light torches to see, and the dome began to fill with smoke.
The cave-people were still angry, because the city looked impressive on the outside, even if it wasn't very pretty on the inside anymore. So the cave-people built devices out of fallen trees to fling large boulders up that would crash into the wall and dome. The city-people became scared again, and piled dirt on top of the wall and dome to protect it from the boulders. Only the entrance remained uncovered.
As they had down to the first city, the cave-people also did to the other cities. Soon all the hills looked the same as the grass grew up again from the new mounds of dirt. There were no cities to see anymore, just hills that each was a little taller now, with a dark opening through which the city-people could come and go. The cities were dark and smokey, and the city-people choked on the smoke. The goat-herds and farms were gone, so everyone had to leave the city in the morning to hunt and gather food and return by night before the animals came out.
The cave-people still hated the city-people, and the city-people the cave-people. After awhile though, they each forgot why they hated the other even though they were both convinced that the hatred was well deserved. The city-people lived in a caves very much like the cave-people, the only difference being their caves were on the tops of hills, though you might never notice them as you looked up.
Eh, came out longer than i was intending. Perhaps i should cut out a lot of the details.