Hata clan was an immigrant clan active in Japan since the Kofun period (250–538), according to the history of Japan laid out in Nihon Shoki (720).
Origins
The origin of the clan has been a debated topic for many Japanese historians and scholars.
Many have suggested different kingdoms of East Asia starting from Baekje, Qin Dynasty, Gaya to Silla.
Ancient accounts
Baekje
The first mention of Hata clan was in Nihon Shoki, describing an immigrant clan (known as "Toraikei (渡来系)" in Japanese) arriving in Japan led by "Yuzuki no Kimi (弓月君)" from Baekje.
According to the Nihon Shoki, during the reign of Emperor Ōjin, Yuzuki no Kimi visited Japan from the Kingdom of Baekje where he stated that he had long wanted to emigrate to Japan, but the Kingdom of Silla would not permit him to do so. Having enjoyed the experience of meeting 120 people of his clan at Mimana. Yuzuki no Kimi left Japan but soon returned, in 283, with additional members of his clan "from 120 districts of his own land".
Some point out to the name of Yuzuki no Kimi being of Korean origin. According to Japanese linguists, "弓月君" could be a direct translation of "Kudara (くだら)" a unique name for Baekje in Japanese. In Old Korean, "弓月" could be read as "Kudara (구달아)" which is thought to have carried over to the Japanese language as being of Baekje descent as both words share the same pronunciation.
Qin Dynasty
Contrary to the accounts made in Nihon Shoki, the Shinsen Shōjiroku (814) claims that Yuzuki no Kimi, was allegedly a descendant of Qin Shi Huang, the first emperor of the Qin dynasty. Thus the reason behind Hata being written with the character "Qin (秦)".
Gaya Confederacy
As mentioned in Nihon Shoki, Yuzuki no Kimi claimed he had 120 people in Mimana, a place name that points to the Gaya confederacy in Korea. Therefore, it has been theorized that the Hata clan had immigrated from Gaya rather than Baekje.
Silla
Though not directly stated in either Nihon Shoki or Shinsen Shōjiroku, modern Japanese scholars theorize Silla was the place of origin of the Hata clan.
Modern analysis and accounts
After extensive research and historical analysis, Japanese historians have concluded that the Hata clan originated from Silla and not any of the previously mentioned kingdoms. The city of Kyoto and Fushimi Inari-taisha (the shrine that officially commemorates the Hata clan) have publicly stated that "despite the ancient records being unreliable, it can be deduced that the Hata clan originates from the kingdom of Silla."
The etymology of "Hata" is believed to be "Hada (肌)" meaning "skin" alluding to the silk produced by the immigrants, or "Hata/Hada (波多)" a Japanese translation of the Korean word "Pada (바다)" meaning "ocean" as they came across the seas. They were later given official titles ranging from "Toroshikō (登呂志公)", "Hatano Sakeno Kimi (秦酒公)" and "Taihata (太秦)" after being recognized as a legitimate clan of Japan.
It is thought that the misconception revolving around the origins of Jinhan (previous kingdom of Silla) being built by Qin Dynasty refugees, first mentioned in San Guo Zhi, was what caused the Silla immigrants to become descendants of the Qin Dynasty in Shinsen Shōjiroku (see History of Jinhan Confederacy). The book is also criticized by modern Japanese historians for putting "Kan (漢)" under "Han Dynasty" and not the three kingdoms of Korea, the same way it put Hata under Qin Dynasty instead of Silla. It also contradicts the claims made in Nihon Shoki (the first and oldest mentioning of Hata) that Yuzuki no Kimi was from Qin Dynasty and not Baekje without providing any substantial evidence. For further context, Nihon Shoki lack any mentions of Qin when discussing about Hata.
Finally, excavations in Hata clan's whereabouts have been of Silla origin. It is also reinforced by the fact that the Miroku Bosatsu statue, "Hōkan Miroku (宝冠弥勒)" in Kōryū-ji, built by the Hata clan was made of woods from Silla (present day South Gyeongsang Province) and was gifted to Japan from Silla in 623 according to the Nihon Shoki.
It is believed that centuries after immigrants from Silla had settled, the author of Nihon Shoki accidentally credited them of Baekje origin (due to Japan's close relationship with Baekje at the time) by providing them a story that would give credence to their position as a Japanese clan. After another century later, when Emperor Saga ordered for a compilation of family names, under the misguided assumption that Silla (Jinhan) was of Qin's origin, it was recorded in Shinsen Shōjiroku that in turn, the Hata clan was originally from the Qin Dynasty.