The Crossbow appeared during the Zhou dynasty invented by Mr. Ch'in of Ch'u around 700 BC; the Wheelbarrow was invented by the prime minister of Shu Han, Zhuge Liang around the "Three Kingdoms" in China at the end of the Han dynasty; the Great Wall of China was built during the era of the first emperor of China Qin Shi Huang, founder of the Qin dynasty; and the writing system was first invented probably simultaneously by both the Olmecs and Mayas around the Gulf of Mexico in "Mesoamerica", and in China with the Shang dynasty.
