17th century and was widely exported from Spain to other European countries and to the Spanish colonies in the Americas.In Morocco, existing architectural styles were perpetuated with relatively few outside influences. Here, traditional zellij continued to be used after the 15th century and continues to be produced up to the present day. Under the Saadi dynasty in the 16th century and in subsequent centuries, the usage of zellij became even more ubiquitous within Morocco and covered more and more surfaces. During the reign of the 'Alawi sultan Moulay Isma'il (1672–1727), zellij was used extensively on the facades of the monumental gates of the new imperial citadel in Meknes. Under the Saadis, the complexity of geometric patterns was increased for the decoration of the most luxurious buildings, such as the Badi Palace (now ruined). Some of the zellij compositions in the Saadian Tombs are among the best examples of this type in situ. In this example, craftsmen employed finer (thinner) mosaic pieces and the thin, linear pieces that form the strapwork are coloured whereas the larger pieces that form the "background" are white. This scheme reversed the colouring pattern generally seen in older zellij (where the ground was coloured and the linear strapwork was white). Over the centuries since the Saadi period, the sgraffito technique previously used for Marinid epigraphic friezes came into more general usage in Morocco as a simpler and more economic alternative to mosaics. This type of tile was often employed on the spandrels of large gateways and portals. The motifs are often relatively simpler and less colourful than the traditional mosaic zellij style. In addition to black glaze, green or blue glaze was also used in later examples of this type to obtain motifs in these colours. An example of this can be seen on the blue and green tiled façades of the Bab Bou Jeloud gate in Fez, built in 1913. In later centuries, the interlacing strapwork that once separated the polygons in geometric mosaics was no longer standard and Moroccan craftsmen created rosette-style geometric compositions on an increasingly large scale. The culmination of this latter style is visible in the palaces built during the 19th and 20th centuries. New colours were also introduced into the palette during this period, including red, a bright yellow, and dark blue. Zellij was employed on a wider array of architectural elements. The geometric rosette motifs were used to decorate