Emperor Guangwu reinstated the Han dynasty with the support of landholding and merchant families at Luoyang, east of the former capital Xi’an. Thus, this new era is termed the Eastern Han dynasty. With the capable administrations of Emperors Ming and Zhang, former glories of the dynasty was reclaimed, with brilliant military and cultural achievements. The Xiongnu Empire was decisively defeated. The diplomat and general Ban Chao further expanded the conquests across the Pamirs to the shores of the Caspian Sea, thus reopening the Silk Road, and bringing trade, foreign cultures, along with the arrival of Buddhism. With extensive connections with the west, the first of several Roman embassies to China were recorded in Chinese sources, coming from the sea route in AD 166, and a second one in AD 284.
Foreign travelers to Eastern-Han China include Buddhist monks who translated works into Chinese, such as An Shigao from Parthia, and Lokaksema from Kushan-era Gandhara, India. In addition to tributary relations with the Kushans, the Han Empire received gifts from the Parthian Empire, from a king in modern Burma, from a ruler in Japan, and initiated an unsuccessful mission to Daqin (Rome) in AD 97 with Gan Ying as emissary. A Roman embassy of Emperor Marcus Aurelius (r. 161–180 AD) is recorded in the Weilüe and Hou Hanshu to have reached the court of Emperor Huan of Han (r. AD 146–168) in AD 166, yet Rafe de Crespigny asserts that this was most likely a group of Roman merchants. In addition to Roman glasswares and coins found in China, Roman medallions from the reign of Antoninus Pius and his adopted son Marcus Aurelius have been found at Óc Eo in Vietnam. This was near the commandery of Rinan (also Jiaozhi) where Chinese sources claim the Romans first landed, as well as embassies from Tianzhu (in northern India) in the years 159 and 161. Óc Eo is also thought to be the port city “Cattigara” described by Ptolemy in his Geography (c. 150 AD) as lying east of the Golden Chersonese (Malay Peninsula) along the Magnus Sinus (i.e. Gulf of Thailand and South China Sea), where a Greek sailor had visited.
The Eastern Han dynasty was one of the most prolific era of science and technology in ancient China, notably the historic invention of papermaking by Cai Lun, and the numerous scientific and mathematical contributions by the famous polymath Zhang Heng.