philosophy Apollonius of Perga, Greek geometer Carneades, Greek philosopher Crates of Mallus, Greek grammarian and philosopher Diogenes of Babylon, Greek philosopher Eight Immortals of Huainan (淮南八仙), Chinese philosophers Hipparchus, Greek astronomer Hypsicles, Greek mathematician and astronomer Liu An (劉安), Chinese geographer Panaetius, Greek philosopher Polybius, Greek historian Posidonius, Greek philosopher, geographer, astronomer and historian Seleucus of Seleucia, Hellenistic astronomer Sima Qian (司馬遷), Chinese historian Zenodorus, Greek mathematician Inventions, discoveries, introductions The Chinese first produce paper. Silk Road between Europe and Asia. Hipparchus discovers precession of Earth's equinoxes and compiles first trigonometric tables. According to legend, Liu An invents tofu. The Fibonacci numbers and their sequence first appear in Indian mathematics as mātrāmeru, mentioned by Pingala in connection with the Sanskrit tradition of prosody. Pingala was the first who accidentally discovered binary numbers in which he used laghu(light) and guru(heavy) rather than 0 and 1. Tube drawn technology: Indians used tube drawn technology for glass bead manufacturing which was first developed in the 2nd century BCE The Roman concrete (pozzolana) first used. A system for sending signs to communicate quickly over a long distance is described by Polybios. The earliest known winnowing machine is depicted in a Han Dynasty Chinese tomb model. See also List of sovereign states in the 2nd century BC. References -8 -98