Encyclopedia of Islam

The peninsula of Arabia lying at the South-West corner of the Asian continent has Syrian Desert in the North, the Red Sea in the West, the Indian Ocean in the South and the Persian Gulf in the East, as its surroundings. There not being much difference in the length and  breadth of the Arabian peninsula, it is almost rectangular in shape and has chains of mountains fencing it on all its three sides except North. Leaving apart the mountain ranges, the country of Arabia can be divided in to six main geographical areas. It speaks much about the nature of the climate of this country that out of these six, four comprise of the different kinds of deserts.The whole of Arabia, except its South-Western corner (Yemen) is an arid country with very high temperatures during daytime under its cloudless skies. It does not has a single river with perennial water sources, while the sporadic rains the country receives, is not more than 4 to 6 inches per year.  With most parts of Arabia consisting of sand deserts or unproductive stony land, and the scarcity of water as mentioned above, it is not surprising if most of the country have been unfit for agriculture. The exception being the areas of 'Aseer and Yemen in the South-West part of the country, or the large or small oasis, spread all over the country with long distances of desert or wasteland between them. These distances till the middle of the 20th century could be covered with caravans of camels only.