Soccer was known in ancient China as Cuju, widely developed as early as in the time of The Warring States. The first monograph of Chinese soccer, "Cuju in 25 chapters", came out onto market in the Han Dynasty (206 B.C. - A.D. 220), while two major improvements in manufacturing engineering of the soccer ball were carried out in the Tang Dynasty (618-907): first, the two-piece ball shell of leather was replaced with eight pieces of sharpened-leather sewn up to a rounded spherical shell; second, the stuffing hair inside the shell was replaced with an animal’s urinary bladder, "aspirated and then inflated", transforming it into an inflated ball. Since the ball became lighter, it could be kicked higher. The goal was set up on two bamboo poles thirty meters in height. In playing methods, the Han Dynasty competed directly in dual meet, while in the Tang Dynasty the goal was set up in the middle of the pitch with each of the two teams taking a side, "whoever shoots more wins the game". Women’s soccer also emerged in the Tang Dynasty. There was no goal in women’s soccer games, but they were judged by kicking height and style, so-called "plain playing". Up to the Song Dynasty (960-1279), soccer had forged ahead laterally in techniques from competing in shooting accuracy to dexterity of ball control. And ball manufacturing had been further improved over that of the Tang Dynasty, using a method of "assembly of twelve scented sectors." The raw materials were tanned leather that was cut out into light pieces. Then technically, the ball was constructed by close, piece-by-piece assembly, without showing any thread. The final ball had to weigh exactly 600 grams and the distance from the centre of the ball, to any point on its surface, had to be the same.