The great Moslem cities of Bagdad, Damascus, Cairo, and Cordova were not only seats of government for the different divisions of the Arabian Empire; they were also the centers of Arabian civilization. The conquests of the Arabs had brought them into contact with highly developed peoples whose culture they absorbed and to some extent improved. They owed most to Persia and, after Persia, to Greece, through the empire at Constantinople, In their hands there was somewhat the same fusion of East and West as Alexander the Great had sought to accomplish. [23] Greek science and philosophy mingled with the arts of Persia and other Oriental lands. Arabian civilization, for about four centuries under the Ommiad and Abbasid caliphs, far surpassed anything to be found in western Europe. AGRICULTURE Many improvements in agriculture were due to the Arabs. They had a good system of irrigation, practiced rotation of crops, employed fertilizers, and understood how to graft and produce new varieties of plants and fruits. From the Arabs we have received cotton, flax, hemp, buckwheat, rice, sugar cane, and coffee, various vegetables, including asparagus, artichokes, and beans, and such fruits as melons, oranges, lemons, apricots, and plums. MANUFACTURING The Arabs excelled in various manufactures. Damascus was famous for its brocades, tapestries, and blades of tempered steel. The Moorish cities in Spain had also their special productions: Cordova, leather; Toledo, armor; and Granada, rich silks. Arab craftsmen taught the Venetians to make crystal and plate glass. The work of Arab potters and weavers was at once the admiration and despair of its imitators in western Europe. The Arabs knew the secrets of dyeing and they made a kind of paper. Their textile fabrics and articles of metal were distinguished for beauty of design and perfection of workmanship. European peoples during the early Middle Ages received the greater part of their manufactured articles of luxury through the Arabs. [24] COMMERCE The products of Arab farms and workshops were carried far and wide throughout medieval lands. The Arabs were keen merchants, and Mohammed had expressly encouraged commerce by declaring it agreeable to God. The Arabs traded with India, China, the East Indies (Java and Sumatra), the interior of Africa, Russia, and even with the Baltic lands. Bagdad, which commanded both land and water routes, was the chief center of this commerce, but other cities of western Asia, North Africa, and Spain shared in its advantages. The bazaar, or merchants' quarter, was found in every Moslem city. GEOGRAPHICAL KNOWLEDGE