This is a very good launching point for studying the influences of Indian civilization upon China (and ultimately, Japan)
Across the Himalayan Gap: An Indian Quest for Understanding China ed. Tan Chung p. 133
” … we find common things in indian adn Chinese legends like Chinese Pangu’s (the creator of Heaven and Earth) bearing resemblance to Indian Purusa. These legends depict Inidan and Chinese landscapes symbolic as the transformations of the bones and fluids of Purusa and Pangu (mountains made of their bones, and bones made of their fluids).
The Chinese knew Kunlun as early as Indians knew Himalaya. According to a Tang scholar of the 7th century, Daoxuan (596-667), “Kunlun” and Himalaya were one and the same.1 Many scholars suspect the Chinese legend of Xiwangmu being of a goddess of Indian origin.
Ancient Chinese heard about the magical power of Indians to call rains whenever they wanted. some Indian Buddhist monks like Vajarabodhi and Amoghavajra etc., demonstrated such a power by playing with the symbol of Naga/ Dragon. We have records of Indian monks presiding over imperial rain-invoking ceremonies when China was visited by severe drought in the years 366, 726, 772 and 889, the last occurred in independent Yunnan — the state of Nanzhao.2 Both India and China were agrocultures (I have coined the term to replace the tongue-twister “agricultural culture”) for which rain-fall assumed great importance. The imaginary powerful Nagaraja/Dragon symbol definitely had a connction with it. We can describe the two civilizations as Snake-Power Twins before the advent of Buddhism in China.
…The mystication of the supernatural power of snake in India and long in China was the product of agroculture of both the countries. While we don’t have concrete evidence for the Indian input in the imagination of the Buddhist Chinese Long, we certainly can trace the Indian influence on the Buddhist (and post Buddhist, if you wish) Chinese Long. For one thing, the artifacts that symbolize Long reated in pre-Buddhist China are by and large, free from the fierce look that typifies the Buddhist Long (like hteChinese say, “zhangya wuzhua” i.e. baring its teeth and waving its claws) which clearly demonstrate the inner social function of Long/Drgon as the guardian of the imperial system. It is in this function that we clearly see the Indian contribution.
To recapitulate what I have spelt out elsewhere, during the pre-Buddhist period, even as late as the Han Dynasty, the Dragon/Long was treated as a “beast” (chu). The famous Han scholar, Wang Chong (27-97?) cited Chinese traditions liek Long being reared so that people could eat its liver.3 But, in Indian legends, Siva was a Naga, Buddha was also a Naga, and the Indian traditions of Nagaraja performing the role of a guardian-angel for the God/Buddha and trhe sacred treasure. It was this message whih was driven home in Chinese oral culture as well as literary tradition. Only after absorbing this cultural function from the Indian Nagarana did the Chinese Long become a close companion of the Chiense imperial families in all dyunasties from Sui-Tang till the Manchu. Another c,ear Cinese borrowing fro mIndia is the “Dragon-King” (Longwang) from the Indian nagaraja. China scholars have found that this cult of Longwang has settled deeply in China’s socio-cultural chemistry as many penetrating studies, like that of Prasenjit Duara, who has included Longwang in his projection of the “cultural nexus of power” in China.4 Longwang/Dragon King is undisputably the symbol of Sino-Indian cultural twinhood that demonstrates the existence of the Snake-Power Twins of India and China.
As culture advanced, the Snake-Power Twins transformed themselves into a new and higher stage of relations. This was brought about by the “Great Carrier” Mahayabna–here I use the Sanskrit word from a non-religious perspective, viewing it as wrought by the Buddhist evangelic movement, let me take up the early Sino-Indian contaacts from the firm ground backed by historical evidence. We are in a position to say that Indians were among the earliest foreigners to know about the Chinese silk and also to engage in its international tradelong before the famous “Silk Road” between Luoyang and Rome became a thriving international phenomenon. The first foreign words for Chinese silk were “cinamsuka” (Chinese silk dress) and “cinapatta” (Chinese silk bundle) enshrined in Kautilyua’s Arthasastra which goes back to the 4th c BC. These was the famaous “Chinese discovery of India” in the 1st c. BC by Zhang Qian (also spelled as Chang Qian (also spelled as Chang Chien) personal enviory of the powerul Han Emperor Wu (reigning from 140-87 BC) When he was sent to Central Central Asia to conclude alliances against the Hun tribes, he saw silk fabrics, the products of the southwestern Chinese province Sichuan, in the market place of “Daxia” (probably Afghanistan or north of it). He was told that the fabrics were re-exported by the Indian merchants to the hinterland of Central Asia.5
When Yunnan was annexed into the Han Empire in the 1st c AD, the Chinese authorities found that among the foreign settlers there was an Indian community named “Shendu” (perhaps a corruption of “Hindu”[Sindhu was an ancient kingdom that stretched along the River Sindhu/Indus in the ancient era of what is today’s modern Pakistan ]) that was “Indians” or “India”. but the Chinese knowledge about “Shendu” went back to as early as the pre-Han days (3rd c. BC according to some ficticious accounts) India also loomed large in the broad rubric “xiyu” (western regions), because if we glean the data from all early Chinese narratives about Xiyi, we definitely find the depictions of India. Another ambiguous rubric is “Daqin” which was connected with India in two ways. First, India was trading with “Daqjn” (denoting Roman Empire) on the sea. Second, ancient Chinese confused Europe with India and other far-away lands which they had had contacts through the sea. For instance, the Chinese records attributed elephant-teeth and rhinoceros as products of Daqin (while these were clearly Indian specialities not as products not produced in Europe). Thus when the Han records say that Daqin was keenly interested in Chinese silk it actually indicated a triangular route of the Chinese export of silk reaching India, and also Europe via India. In 166 AD, the Chinese recorded the arrival of an embassy probably sent by the Roman Emperor, Mareus Aurelius Antonius, in the Han court. The Roman embassy arrived by sea and landed somewhere near the present Guangdong province in southern China, and journeyed to the Han capital, Luoyang, by road. The embassy made a present to the Chinese emperor which contained ivory, rhinoceros’ horn (a precious ingredient for Chinese medicine) and the shell of hawksbill turtle, all products of India.6 From these accounts, we see fairly brisk contacts between the two great civilization across great distance either through Central Asia overland, pr over the sea. This would not exclude the direct trans-Himalayan contacts as well. Only when there were contacts could legends travel between these two civilizations.”
JAPANESE MYTHOLOGY & FOLKLORE 