In the Sui and Tang periods (589-907), the general pattern of porcelain production was often summarized as "celadon in the south, whiteware in the north". Henan became a major center of porcelain production. White porcelain made in Henan features a transparent glaze and pure color, as white as crystal jade, and was offered as tribute to the imperial court. Major kilns in Henan include the Gongyi, Xiangzhou, Hebi kilns. Speckle-glazed porcelain from the Duandian kilns in Lushan and the productions from the Huangye kilns in Gongyi, such as tri-color glazed pottery, marbled ceramics  and the earliest blue-and-white porcelain, fully exhibit the innovative and ingenious artisanship of pottery and porcelain production during the Tang dynasty.