From 'Marco Polo' by Isaac Asimov published in 1926
Baghdad is a large city, heretofore the residence of the Calif of all the Saracens, as the Pope is of all Christians. A great river flows through the midst of it, by means of which the merchants transport their goods to and from the Sea of India; the distance being computed at seventeen days' navigation, in consequence of the windings of its course.
In Baghdad there is a manufacture of silks wrought with gold, and also of damasks, as well as of velvets ornamented with the figures of birds and beasts. Almost all the pearls brought to Europe from India have undergone the process of boring, at this place. The Mahometan law is here regularly studied, as are also magic, physics, astronomy, geomancy, and physiognomy. It is the noblest and most extensive city to be found in this part of the world.
The Calif, who is understood to have amassed greater treasures than had ever been possessed by any other sovereign, perished miserably under the following circumstances. At the period when the Tartar princes began to extend their dominion, there were amongst them four brothers, having subdued the country of Cathay, and other districts in that quarter, they were not satisfied, but coveting further territory, they conceived the idea of Universal Empire, and proposed that they should divide the world amongst them.
With this object in view, it was agreed that one of them should proceed to the east, that another should make conquests in the south, and that the other two should direct their operations against the remaining quarters.
The Southern portion fell to the lot of Alau, who assembled a vast army, and proceeded in the year 1255 to the attack of this city of Baghdad. Being aware, however, of its great strength and the prodigious number of its inhabitants, he trusted rather to stratagem than to force for its reduction, and in order to deceive the enemy with regard to the number of his troops, which consisted of a hundred thousand horse, besides foot soldiers, he posted one division of his army on the one side, another division on the other side of the approach to the city, in such a manner as to be concealed by a wood. Then placing himself at the head of a third, advanced boldly to within a short distance of the gate.
The Calif made light of a force apparently so inconsiderable, and confidently thought of nothing less than its entire destruction, and for that purpose marched out of the city with his guards. But as soon as Alau perceived his approach, he feigned retreat before him, until by this means he had drawn him beyond the wood where the other divisions were posted. By the closing of these from both sides, the army of the Calif was surrounded and broken, and he was made prisoner, and the city surrendered to the conqueror.
Upon entering it, Alau discovered, to his great astonishment, a tower filled with gold. He called the Calif before him, and after reproaching him with his greediness, that prevented him from employing his treasures in the formation of an army for the defense of his capital against the powerful invasion with which it had long been threatened, gave orders for his being shut up in this same tower, without sustenance; and there, in the midst of his wealth, he soon finished a miserable existence.