Foundation Period By hudsperi 146 end of Alexander's Hellenistic Empire 146 BCE 206 end of the Qin Empire 206 BCE 207 start of the Han Empire 207 BCE 221 start of the Qin Empire 221 BCE 226 end of the Partian Empire 226 BCE 260 date Ashoka began promoting Buddhism 260 BCE 313 date Constantine issued edict allowing Christianity 313 320 start of the Gupta Empire 320 AD 321 start of the Mauryan Empire 321 BCE 323 start of Alexander's Hellenistic Empire 323 BCE 476 end of the Roman Empire 476 AD 550 end of the Gupta Empire 500 AD Oct 21, 1925 end of the Han Empire 25 AD Oct 21, 1927 start of the Roman Empire 27 BC Mar 2, 2022 start of the Partian Empire 248 BCE Mar 2, 2022 end of the Mauryan Empire 185 BCE