Farther east, in the Tigro-Euphrates valley, a tradition of ceramic wall decoration was early established. (See WESTERN ASIATIC ARCHITECTURE.) This took the form of glazed and enam elled bricks rather than tiles proper. It is, nevertheless, important, as being one of the first attempts to cover large and continuous wall surfaces with a decorative, ceramic material, and the friezes of marching beasts from Chaldean and Babylonian palaces, from the later Assyrian palaces and from their Persian successors, the famous friezes of the archers and the lions from the early 4th century palace of Artaxerxes II. at Susa, have remained models of this type of decorative work ever since. (See illustra tion of the Gate of Ishtar at Babylon, under BRICKWORK.) More over, the tradition of fine ceramic work continued vital throughout the stormy period of the fall of the Roman empire and the Mohammedan conquest. It is in Syria, the Tigro-Euphrates valley and Persia that wall tiles were, undoubtedly, first made. Thus tradition relates that the lustre tiles of the mosque of Sidi Okba at Kairouan were brought from Baghdad in 894, and it is certain that by the 13th century the manufacture of wall tiles for both exterior and interior use was well established in various centres in Persia, notably Rhages and Veramine. The exterior use of wall tiles was most highly developed, and in Persia, also, the transition from enamelled and modelled brick to true, thin tile can easily be seen. By the I5th century tile decoration was supreme in Persia and the character had changed. Mosaics and mouldings in relief yielded to a flat treatment with the richness entirely in the coloured, foliated ornament and the inscriptions painted on the' tiles themselves. In later Persian art there is no distinguishable difference between the tiles of the exterior and the interior.
It was these Persian tiles which governed the taste of the eastern part of the Mohammedan world; the same running patterns of leaves, palmettes, the carnation and other flowers that appear on Persian carpets, decorate alike the interiors of mosques in Persia, Mesopotamia and Turkey, from potteries as far apart as Rhodes, Damascus and Kutayieh. In colour these have, universally, a blue-white ground with patterns predominantly blue and green and lesser touches of vermilion and rose and occasional yellows. Several potteries in Asia Minor still operate and produce exquisite wall tiles in the traditional patterns and colours. Because of the gracious delicacy of the interlacing stems and the careful spacing of the leaves and flowers, together with a spring-like clarity of the colours, these Turkish, Syrian and Persian wall tiles are among the most perfect wall decorations of their type.
plaque from Malaga at the beginning of the 15th century in the collection of M. de Osma, in which the patterns are of an almost Persian freedom, with twining foliage, in the greater number the design was almost purely geometric, being formed of interlacing lines that generate 8- and 10-pointed stars, octagons, irregular pentagons and similar figures. There are, in addition, a great many early tiles from the 13th and 14th centuries in which the influence of Christian heraldry is dominant. Even in the transitional plaque mentioned above, coats of arms appear and it is evident that the Mohammedan potters produced much purely heraldic tile work for Christian consumption. Many of these tiles are rich with metallic lustre decoration ; the chief colours are blue, green and brown, with white lines, and in the later work a growing use of black and yellow. The earliest examples of Moorish wall tiles produced their geometric patterns by a mosaic method in which each bit of separate colour is formed by a separate tile. In order to develop a more facile method of producing the same effect, the technique known as cuerda seta (dry cord), in which the tiles are rectangular, and the pattern on each tile is formed by raised fillets between the different colours, which prevented the adjoining enamels from running together. After the Christian conquest a third method was introduced, called cuenca (bowl), somewhat similar to the northern Gothic process in which the portions to be coloured were depressed and then filled with their enamels. These tiles, even in their old traditional Mohammedan patterns, were popular throughout the 16th century and even later for wainscots in Renaissance houses. The potters were evidently Moors; the great centres of manufacture remained as before in Malaga, Valencia, Granada and Seville. In the 16th century the Italian maiolica type of tile was introduced by Francesco Niculoso of Pisa, and these Spanish maiolica tiles were much used, as in the door of the convent of S. Paula at Seville (early 16th century) or the exquisite altar-piece in the Alcazar at Seville made by the same artist in 1503, where the design is purely Italian. Both the cuenca and the pisano or ma jolica types of tile have been made in Spain almost continuously ever since, and the recent years have seen a great increase in the Spanish tile output both in Spain and for export.
Meanwhile in Germany there had been developing a type of tile used principally for stoves, with ornament in relief and a glaze of green, yellow or brown. This tile was in widespread use as early as the 14th century and many examples exist throughout Germany, upper Austria and Switzerland, in which the ornament is of great richness, with Gothic architectural forms in the earlier types and Renaissance forms later.