人类从森林里走出来,从巢居到穴居,从依靠自然野果、树叶为生到依靠农产品生活,从原始社会到奴隶社会,经历了漫长的岁月,经历了巨大的变革。人类为了防寒避暑和防止野兽侵袭,建筑房屋,筑砌城堡,进行物品交换,出现了城堡和市场。据记载,最早的城市出现在5000年以前,主要分布在灌 Humans have come through a long period of experience and have undergone tremendous changes since they came out of the forest, lived from nests to cave houses, relied on natural wild fruits and leaves for their livelihoods and relied on the livelihood of agricultural products, from primitive society to slave society. Human beings in order to prevent summer and prevent the invasion of wild animals, building houses, building masons, the exchange of goods, the emergence of the castle and the market. According to records, the earliest cities appeared in 5000 years ago, mainly in irrigation