Short answers, pulled from the story.
Sino-Roman relations refers to the contacts between the Roman Empire and successive Chinese dynasties, which were primarily indirect. Direct contact was inhibited by intermediate empires, especially the Parthians and Kushans, who sought to maintain control over the lucrative silk trade and actively discouraged the two powers from meeting.
Gan Ying was an envoy sent westward in 97 AD by the Eastern Han general Ban Chao. He reached Parthia and the Persian Gulf but was dissuaded by Parthian sailors from sailing further, told the crossing was dangerous and could take two years. He returned to China with new information about western countries but never reached Rome.
The first recorded Roman embassy arrived in China in 166 AD at the court of Emperor Huan, claiming to come from a ruler named Andun, which corresponds to either Emperor Antoninus Pius or Marcus Aurelius Antoninus. The mission entered China from the south through present-day Vietnam, bringing gifts of rhinoceros horn, ivory, and tortoise shell. Most historians believe the visitors were Roman merchants rather than official diplomats.
Roman knowledge of silk came from accounts of the Seres people of the Far East. In his Natural History of 77-79 AD, Pliny the Elder estimated that Rome's spending on silk and other luxuries from the Far East and India drained roughly 100 million sesterces per year from the Roman economy, prompting a Senate edict in 14 AD prohibiting men from wearing silk.
Roman glassware has been found at Han-period Chinese archaeological sites, including a blue soda-lime glass bowl from Guangzhou dating to the early 1st century BC and a mosaic-glass bowl from a prince's tomb near Nanjing dated to 67 AD. Roman coins and medallions from the reigns of Antoninus Pius and Marcus Aurelius were found at Óc Eo in Vietnam, and a coin of Maximian has been found in Tonkin. Roman glass beads have been discovered as far as Japan.
From the Han dynasty onward, Chinese records called the Roman Empire Daqin, meaning Great Qin. Historical linguist Edwin G. Pulleyblank explains that Chinese historians conceived of Daqin as a counter-China at the opposite end of their known world, and scholar Krisztina Hoppál notes that the Chinese regarded it as a distant and therefore mystical country. The later term Fulin was used for the Byzantine Empire during the Tang dynasty.