What are the positive and negative effects of the ASEAN?

Why do people migrate? And what are the positive and negative effects?(ancient times, not modern)?

• Positive and negative effects for both the place they migrate into and for the people who are migrating. I have to do this essay and have been researching for hours but cant find any info! Help please!! THANK YOU SO MUCH TO WHO EVER ANSWERS THIS!!!!

• Answer:

  In Ancient Times. early Humans did nothing but migrate, because they were 'Nomads.' They lived in caves or crude shelters and they moved on when resources became scarce or the seasons changed. Those kinds of Humans were called 'Hunter Gatherers. There would have been a clear division of labour, whereby the male would do the hunting and the female carried the baby and gathered roots, berries, fruits and hunted small animals like rabbits and birds. He carried a spear and flint knives and axes. She tied a length of buckskin across her back to make a baby-sling, freeing her hands and making her truly mobile and a sharp-eyed naturalist. They left Africa some 70,000 years ago and started a trek which led them, world-wide, to conquer the planet and become Top Predator. New resources and competition always drove them on. Further and further away from Africa, across the continent until they reached the far shores of Mongolia and Russia. Ice covered the stretch of water between Russia and Alaska, so they were able to cross The Bering Straights and pour into Alaska and make their way down the Ice Free Corridor into, first North America and then down, and further down, into South America and all the way to Cape Horn. You could say, 'Always seeking New Pastures,' but it wasn't the pasture they were after, it was the Game that fed on the pastures which made them perpetual Migrants and Nomads. They only stopped doing that when they first started to learn the basics of farming and for the very first time. stopped the migrations and settled in permanent places.