According to the Lokapaññatti, an 11th-12th century Pali text, the Romans had experts in building mechanical automatons or "spirit movement machines". Knowledge of their manufacture was a well-guarded secret, so much so that any expert who tried to leave Rome would be "hunted down and killed by one of his own robots."
The story goes on about how one Roman and his son manage to smuggle the knowledge to India, and robot guardians are made for the purpose of guarding the Buddha's relics.
The first information about anything to the West of the Xiongnu Empire came about as a result of a long, strange journey on the part of the explorer Zhang Qian. This trip would take Zhang almost 14 years to complete (139-126 BC), and resulted in him being held prisoner for more than a year... twice... by the Chinese' arch-enemy at the time.
Zhang Qian’s report described in great detail the kingdoms he had personally visited or traversed. Zhang’s report, as relayed through Sima Qian’s Shiji, itself translated by Dr. Burton Watson:
• the Dayuan/Ionian Kingdom, whom Zhang described as “southwest of the territory of the Xiongnu, some 10,000 li (5,000 kilometers) directly west of China. The people are settled on the land, plowing the fields and growing rice and wheat. They also make wine out of grapes. The people live in houses in fortified cities, there being some seventy or more cities of various sizes in the region. The population numbers several hundred thousand"
• the Yuezhi, described as “The Great Yuezhi live some 2,000 or 3,000 li (1,000 or 1,500 kilometers) west of Dayuan, north of the Gui (Oxus) river. They are bordered to the south by Daxia (Bactria), on the west by Anxi, and on the north by Kangju. They are a nation of nomads, moving place to place with their herds and their customs are like those of the Xiongnu. They have some 100,000 or 200,000 archer warriors."
• Daxia/Bactria, described as “situated over 2,000 li (1,000 kilometers) southwest of Dayuan, south of the Gui (Oxus) river. Its people cultivate the land, and have cities and houses. Their customs are like those of Dayuan. It has no great ruler but only a number of petty chiefs ruling the various cities. The people are poor in the use of arms and afraid of battle, but they are clever at commerce. After the Great Yuezhi moved west and attacked and conquered Daxia, the entire country came under their sway. The population of the country is large, numbering some 1,000,000 or more persons. The capital is Lanshi (Bactra) where all sorts of goods are bought and sold."
• the northern kingdom Zhang called the Kangju, which may have been of either Turkic, Iranian, or Tocharian origin, described as “situated some 2,000 li (1,000 kilometers) northwest of Dayuan. Its people are nomads and resemble the Yuezhi in their customs. They have 80,000 or 90,000 skilled archer fighters. The country is small, and borders Dayuan. It acknowledges sovereignty to the Yuezhi people in the South and the Xiongnu in the East."
He also made mention of many other peoples and kingdoms he had heard of or discussed while abroad, including:
• Anxi (the Parthian Empire which was a kind of successor state to the ancient Persian Empire), "Anxi is situated several thousand li west of the region of the Great Yuezhi. The people are settled on the land, cultivating the fields and growing rice and wheat. They also make wine out of grapes. They have walled cities like the people of Dayuan, the region contains several hundred cities of various sizes. The coins of the country are made of silver and bear the face of the king. When the king dies, the currency is immediately changed and new coins issued with the face of his successor. The people keep records by writing on horizontal strips of leather. To the west lies Tiaozhi."
• Tiaozhi (which remains ill-defined, but might have been Mesopotamia), described as, “situated several thousand li west of Anxi and borders the Western Sea (probably either Persian Gulf or the Mediterranean). It is hot and damp, and the people live by cultivating the fields and planting rice... The people are very numerous and are ruled by many petty chiefs. The ruler of Anxi gives orders to these chiefs and regards them as vassals.
• Shendu (Northern India/Pakistan), saying, "Shendu, they told me, lies several thousand li southeast of Daxia (Bactria). The people cultivate the land and live much like the people of Daxia. The region is said to be hot and damp. The inhabitants ride elephants when they go in battle. The kingdom is situated on a great river (Indus)."
More legendarily, one of the most famous fictional works is the 16th century work Xi You Ji, or "Journey to the West" (often tranlated into English simply as "Monkey"). It tells the fantastical tale of the Buddhist monk Xuanzang (aka Tripitaka) being dispatched by the Emperor to retrieve Buddhist Sutras from the Far West (meaning in this case, India). He was joined by what is effectively the Trickster Monkey God Sun WuKong, as well as the pig-monster Zhu BaJie, a banished celestial General called Sha WuJing, and a white dragon who has been turned into a horse for the duration of the journey called Bai LongMa... all of whom are trying to get back into heaven by making sure the Monk doesn't get eaten along the way by the many, many demons who would love nothing more than to devour pure, holy flesh. Hijinks ensue.
Once they finally get to The West, it is depicted in highly fantastic way... and strangely simultaneously as a sort of paradise on Earth, but still with legions of demons for the to overcome. It's a great read... though you can kind of flip through most of the middle which is pretty much a fomulaic serial of "Monk is captured, protectors must rescue him, McGruffin/Monkey does something amazing, Monk is rescued, the journey continues... tune in next week!"
Here's the English version I have at home: Monkey
Watson, Burton (1993), Records of the Grand Historian of China. Qin Dynasty.
Shiji (Mandarin)
One final note, if listening is your bag, I suggest checking out The History of China Podcast. I make it, and we've got a whole episode on Zhang Qian's trip. At current were in the beginning of the 6th century CE. Cheers!