were widespread in China. Thyroid hormones to treat goiters: In 239 BC, Master Lu's Spring and Autumn Annals stated that where water is too light, people suffer widespread baldness and goiter. It was not until the 1860 that French physician Gaspard Adolphe Chatin (1813–1901) linked goiter with the lack of iodine in soil and water; iodine was discovered in the thyroid gland in 1896 by German chemist Eugen Baumann, while thyroid extract was used to treat patients in 1890. The Tang Dynasty (618–907) physician Zhen Quan (d. 643 AD), in his Old and New Tried and Tested Prescriptions, stated that the thyroid glands taken from gelded rams were used to treat patients with goiter; the thyroid hormones could be swallowed in pill form (the body of the pill made from crushed jujube pulp) or as a solid thyroid gland with the fat taken off. The Pharmacopoeia of the Heavenly Husbandman asserted that iodine-rich sargassum was used to treat goiter by the 1st century BC (Ge Hong, 284–364, also suggested using a tincture derived from sargassum seaweed in about 340 AD), a treatment later recorded in the Western World by Italian practrica Roger of Palermo in his Practica Chirurgiae of 1180 AD. Tofu: Although both popular tradition and Song Dynasty philosophers like Zhu Xi (1130–1200 AD) credit the invention of tofu—along with soymilk— to Liu An (179–122 BC), a Han-Dynasty King of Huainan, no mention of tofu is found in the extant Huainanzi (compiled under Liu An). The earliest known mention of tofu was made in Records of the Extraordinary (Qingyi lu 清異錄), which reported that tofu was sold at Qingyang (Anhui). The earliest explanation of how to make tofu is found in the Bencao Gangmu, written by the Ming dynasty polymath Li Shizhen (1518–1593). According to Liu Keshun (1999), Liu An's process for making tofu was essentially the same as today. Toilet paper: Toilet paper was first mentioned by the Sui Chinese politician and artist Yan Zhitui (531–591) in the year 589 during the Sui Dynasty, with full evidence of continual use in subsequent dynasties. By the mid 14th century during the Yuan Dynasty (1271–1368), it was written that ten million packages of 1,000 to 10,000 sheets of toilet paper were manufactured annually in Zhejiang province alone. Traction trebuchet: The earliest type of trebuchet catapult was the traction trebuchet, developed first in China by the 5th or 4th century BC,