The reason for this is that sedentary people have become used to laziness and ease. They are sunk in well-being and luxury. They have entrusted the defence of their property and their lives to the governor and ruler who rules them, and to the militia which has the task of guarding them. They find full assurance of safety in the walls that surround them, and the fortifications that protect them. No noise disturbs them, and no hunting occupies their time. They are carefree and trusting, and have ceased to carry weapons. Successive generations have grown up in this way of life. They have become like women and children, who depend upon the master of the house. Eventually, this has come to be a quality of character that replaces natural disposition.
The Bedouins, on the other hand, live apart from the community. They are alone in the country and remote from militias. They have no walls or gates. Therefore, they provide their own defence and do not entrust it to, or rely upon others for it. They always carry weapons. They watch carefully all sides of the road. They take hurried naps only when they are together in company or when they are in the saddle. They pay attention to the most distant barking or noise. They go alone into the desert, guided by their fortitude, putting their trust in themselves. Fortitude has become a character quality of theirs, and courage their nature. They use it whenever they are called upon or roused by an alarm. When sedentary people mix with them in the desert or associate with them on a journey, they depend on them. They cannot do anything for themselves without them. This is an observed fact. (Their dependence) extends even to knowledge of the country, the directions, watering places, and crossroads. Man is a child of the customs and the things he has become used to. He is not the product of his natural disposition and temperament. The conditions to which he has become accustomed, until they have become for him a quality of character and matters of habit and custom, have replaced his natural disposition. If one studies this in human beings, one will find much of it, and it will be found to be a correct observation.
[Muqaddimah by Ibn Khaldun, p.94-95]