Answer:
Because the desert dwellers could not grow crops, many herded sheep and camels. The areas along the coasts generally had milder climates that could support greater numbers of people. Towns grew up in these areas, and the townspeople became traders.The water supply in Saudi Arabia, and specifically the lack of water has always been the major constraint on agriculture and the determining factor on where cultivation occurred. The kingdom has no lakes or rivers. Rainfall is slight and irregular over most of the country.One of the major cultures that dominated the Arabian Peninsula just before the rise of Islam was that of the nomadic Bedouin people. The polytheistic Bedouin clans placed heavy emphasis on kin-related groups, with each clan clustered under tribes. The immediate family shared one tent and can also be called a clan.