Time Tangled Island: Ancient China Factropica Fast Facts and quizzes by Mark Hughes Related Links Great Wall of China Famous Buildings and Structures Seven New Wonders Try our Great Wall of China Quiz! Factropica Fast Facts Chinese astronomers made the first recorded sighting of Halley's Cometin 240 B.C. The Chinese have been using wheeled vehicles for the last 3,500 years. Chinese mathematicians were among the first to use powers of 10 to express magnitudesand to use negative numbers. The lessons of Confuciuswere written down around 470 B.C. His teachings are notable for being ethical rather than religious, for example, centering on the golden rule of doing to others as one would have done to oneself. From 214 B.C. to 206 B.C., General Meng Dian began connecting the existing defensive walls in northern China in order to form a single fortified system that became known as the Great Wall of China. The wall became the largest human building project in history. Chinese scholars recognized the connection between ocean tides and the phases of the moon about 2,200 years ago. The Silk Road was a trade route connecting China to Europe, a distance of 8,000 miles (12,800 km). In addition to defense, the Great Wall of China was used to store and protect state documents, which were written on paper. Gunpowder was invented in Chinaaround 270 A.D. It was first used to make fireworks. About 1,500 years ago, the Chinese were making flying toys that used horizontal propellers to slow their descent. That practice is similar to modern day helicopters.