This whole thing isn't a debate anymore, and we kind of suffer because the book at this point is a bit aged.

It must be noted that Benedict Anderson with his Imagined Communities is mainly aiming to make his personal critique of the concept of nationalism (and, in fact, his idea of the 'imagined community' as the nature of the nationalistic group is still rather central to much of modern social sciences). Regardless of your personal view on the benefits or dangers of nationalistic mindsets, it is important to keep in mind that Anderson aims to criticise them in the book and, with his footnote, wants to ridicule the Japanese monarchy as the central component of Japanese (ethno-)nationalism that it was (and is). The aim of the footnote is primarily to discredit the legitimacy of Japanese nationalism and, by extension, the various horrors committed under its banner by Japanese forces, particularly between the 1890s and the 1940s.

My personal verson is the Second Edition of 1991, so there might be minor differences between mine and yours.

But, and this is interesting, I also have the footnote you describe. Precisely, it is on page 96.

While the Japanese spoken in Kyushu was largely incomprehensible in Honshu, and even Eda-Tokyo and Kyoto-Osaka found verbal communication problematic, the half-Sinified ideographic reading-system was long in place throughout the islands, and thus the development of mass literacy through schools and print was easy and uncontroversial. Second, the unique antiquity of the imperial house (Japan is the only country whose monarchy has been monopolized by a single dynasty throughout recorded history), and its emblematic Japaneseness (contrast Bourbons and Habsburgs), made the exploitation of the Emperor for official nationalist purposes rather simple. [29] Third, the penetration of the barbarians was aprubt, massive, and menacing enough for most elements of the politically aware population to rally behind a programme of self defence conceived in the new national terms.

Footnote 29 reads as follows:

But I have been informed by scholars of Japan that recent excavations of the earliest royal tombs suggest strongly that the family may originally have been - horrors! - Korean. The Japanese government has strongly discouraged further research on these sites.

So, while I cannot personally confirm it, I would make the guess that the First Edition has this very same footnote in the very same passage, putting the date of the claim all the way back to the year 1983, when the book was originally published. This is significant because that means that the book was written during the Showa Era, the reign of the Japanese emperor Hirohito - the very same Hirohito who led his country into World War 2 through, at the very least, his passive tolerance of the actions of his military leadership, if not his active encouragement of the wars of aggression waged upon Korea, which has so often become a victim of the power plays and rivalries between its two big neighbors, Japan and China. So the context in which the book is written is one where the Japanese monarchy was far more conservative and reactionary than the monarchy we know today (and what a date to write about this, as today the emperor Akihito has abdicated in favor of his son).

The new Emperor, Hirohito's son Akihito, on the throne since 1989, plays into this story because he accepts the ties between the Japanese monarchy and Korea.

I, on my part, feel a certain kinship with Korea, given the fact that it is recorded in the Chronicles of Japan that the mother of Emperor Kammu was of the line of King Muryong of Paekche.

• Akihito, December 2001 (see also this report by the Guardian and this one from the New York Times).

So, what we are dealing with here is a classic case of outdated information. At the time than Anderson initially wrote the book, the Japanese narrative would not have allowed for any ties to Korea. But the deeply flawed Hirohito has made space for his much more open-minded and approchable son (and now, a grandson whose character will show itself in the upcoming decades).

Akihito, by openly embracing the ties between his bloodline and the Korean people, as well as his relaxed public image and his personal apology offered to the President of South Korea Roh Tae-Woo in 1990, has made admirable progress in mending the historical animosities between Japan and Korea that were driven to the extreme by the actions of his father.

So, no, no more research is necessary. The Japanese emperor admitted his Korean heritage.

Hmmm. Truthfully, I wasn't familiar with this particular claim concerning royal tombs. However, there is precedent for some controversy over the (likely) foreign origins of the Japanese royal line.

Note: A lot of this is owed to remarks made by Emperor Akihito on December 23rd, 2001, which unfortunately falls within our sub's 20-year limit. Further complicating things is the context in which he made these remarks, which is how I found out about them in the first place. North Korea's my usual specialty and you'd think this would be a little out of the way, but soccer's one of my hobby fields, and ...

Q: Who jointly hosted the 2002 World Cup?

A: South Korea and Japan.

Q: Was it a long, difficult, and expensive process made even harder and more diplomatically nightmarish by Japan's colonization of Korea between 1910 and 1945 and its repressive and exploitative treatment of Koreans during World War II?

A: Does the Pope shit in the woods?

Anyway, I'll try to keep to historical concerns. Japan isn't my field and I hope you'll get someone with a better handle on this, but maybe it'll be a little helpful regardless.

The short answer is yes: Japan's imperial family is likely part Korean in origin: Akihito gave a press conference on his 68th birthday in December 2001 and said:

(Korea) contributed greatly to Japan's subsequent development ... I, on my part, feel a certain kinship with Korea, given the fact that it is recorded in the "Chronicles of Japan" that the mother of Emperor Kanmu was of the line of King Muryeong of Paekje.

The "Chronicles of Japan" that the emperor was referring to is a series of works well-known to East Asia scholars. In the early 8th century, the Japanese imperial family commissioned a history of the nation and its own bloodline. Some of what resulted, particularly in the first volume -- e.g., collections of folk songs, stories about the creation of the world and the rise of the gods, the divine rights of the imperial family, a suspiciously convenient set of excuses for military failures, and some fudged dates to make the family look older than it actually was -- isn't really what we'd expect out of history books today. It doesn't matter. Honestly, it's stellar work for its time, and it's an invaluable window into the period and a foundation text if you're serious about Japanese history and culture.

The second volume, the Nihon Shoki (日本書紀) was completed in ~720 CE. It describes how King Muryeong of Paekje sent his second son, Junda, to Japan as a diplomatic envoy with tribute in 505 CE. Paekje was one of three Korean kingdoms in this period (known, with impeccable logic, as the Three Kingdoms period), located on the southwestern portion of the peninsula. Paekje was a regional naval power with extensive trade links to both Japan and China, and Muryeong already had ties to the Japanese throne. His uncle had served Emperor Yuryaku, and Muryeong himself is recorded by the Nihon Shoki as having been born on an island in Japan. Anyway, Muryeong's son Junda remained in Japan for the rest of his life, leaving children when he died in 513 CE.

Roughly two centuries after Junda's death, his great-great-great-great-great-great granddaughter (1), Yamato no Niigasa, was born in 720. She became the consort of Prince Shirakabe (later Emperor Konin) at what we would consider to be a horrifyingly early age. In 736-7, she gave birth to Prince Yamabe, who became Emperor Kanmu in 781 after his father abdicated. It was actually during Kanmu's reign in 797 that the third volume of imperial history, the Shoku Nihongi (続日本紀) was completed, recording the aforementioned.

So you don't actually have to go digging anywhere to find evidence that the Japanese imperial family is partly descended from a Korean bloodline. It's literally there in the court records.

But are the imperial records accurate? Always a good question. When examining the histories, scholars generally distinguish between: a). the material that's pretty baldly intended to shore up the legitimacy of the imperial family (e.g., its descent from the goddess Amaterasu, and records of the earliest emperors, whose existence no one's been able to verify), and: b). the material that they can confirm with other sources or that appears to have been an apolitical record of events at court. For example, portions of the Nihon Shoki record when refugees from Silla (the Korean kingdom on the southeastern portion of the peninsula) arrived and were given land, and when members of the royal family travel to the hot springs. We know that infighting between the Korean kingdoms sent people to Japan, and the Nihon Shoki references a number of Korean place names that the Japanese imperial court is otherwise unlikely to have known. And while we can't necessarily verify, say, a trip to an inn built around hot springs, we know that that was (and remains) a normal thing in Japanese culture. Interestingly, the oldest inn in Japan dates to 705, before the Nihon Shoki was completed.

As an aside, if you've been keeping up with the news, you'll likely have seen reports that Emperor Akihito has abidicated (as of today, as a matter of fact).

(1) I really hope I got that right and apologize if I didn't. I had to resort to counting on my fingers multiple times. Genealogy is not my strong suit.

I'm going to respectfully disagree with /u/ted5298 and his answer that it isn't a debate anymore just because the Emperor admitted to his Korean heritage. Regardless of what the Emperor might say, evidence points to parallel emergence of kingship rather than Korean origin and a very strong Japan line.

Short answer: the imperial family is one of native origin as part of parallel paths to kingdom emergence in the region. The Korean ancestry may be attributed to Kammu's mother, but only after a line of distinct Japanese rulers. It's akin to say I'm French because even though my family originates in the slavic countries, my great great great grandfather married a French woman and no other French-born individuals joined my family.

Regardless, the issue is a source of contention for political reasons. I'd view Akihito's statements as more diplomatic than anything.

Long answer-

We have to start with a timeline: kingship and state formation in Japan (including imperial lineage) in Japan doesn't really start to take place until the 1st century BC in the Yayoi period. This is the age of Himiko, and as a number of written histories predating the Nihon Shoki and Kojiki state (such as the Records of Wei ( 魏志 ), early 5th century AD). Various historians have discussed the "tribal alliances" and others "an early state." Neither have been convincingly defending in recent scholarship. But recent archaeological discoveries at Yoshinogari in Kyushu's Saga prefecture point us to what likely was the first "seat of hierarchy of hamlets." A doubled-moated settlement with a sizable adjacent mounded tomb has been excavated. Deep pillar holes suggest the double-moated areas had lookout towers similar to those described in the Records of Wei. Excavations of the area yields bronze daggers similar to those found in Korea, glass beads from south China, baskets, pottery, and other artifacts of note. This is important because excavation of surrounding areas do not yield metal tools from the time, indicating that Yoshinogari-kuni (kuni 国 = "country"... or region/hamlet in these cases) dominated, in part, through their use of metal.

It’s also important to see that diplomacy and trade existed between the Yamatai and the mainland as early as the first century BC, implying that a social hierarchy existed in which communication between the lands occurred. Such occurrences are only natural considering increased cooperation between peoples yields to an increased need for a common "law" which allows for a leader (usually a charismatic one) to emerge and take on the chiefly mantle. And, naturally, with the emergence of a sole chiefton comes both those who would seek to have that role for themselves and the need for those in the chiefly position to revalidate and legitimize their authority over non-kin within the kuni. The excavations of Yoshinogari mentioned previously also yielded corpses, arrowheads, and other weapons of war (not to mention evidence of military towers) that showed how expansion wasn’t always peaceful; each kuni would have different ideas of power and authority that needed to be dealt with and validated. Most times these validations would take the form of religious functions normally reserved for local leaders in kin-based communities.

This is the second important thing to note: what rulership entails. What would begin with religious claims to rulership would need to grow as leaders needed to provide protection for those under him and to allocate natural resources. This would lead to tribute collection and increased administrative action from the leader down throughout the hierarchy, forming a "ceremonial center" of sorts where the sacerdotal chief and his administrative assistants (plus guards to keep him in power) ruled over the peasantry whose sole purpose really was to produce that which could be absorbed into the kuni’s resource pool. Well, sole purpose might be too strong of a word; peasantry was also expected to provide military service for their chief.

We now turn to Queen Himiko (the non-mythical version). Taking a hint from previous peninsula leaders, some of Himiko’s first actions were to send tributes to the Chinese Emperor Wei ( 魏 ). Emperor Wei responded, conferring the title "Queen of Wa, Friend of Wei" upon her and sending back ornate gifts to serve as her regalia. This title from the most advanced civilization in the Far East furthered her validation and authority amongst the state-to-be of Wa and such a "stamp of approval" would become the patent necessary for participation in diplomacy and trade within the Far East region (mainly China, Korea, Japan). China's "seal of approval" granted access to advancements at court and with technology while also granting the ruler the right to redistribute the fruits gained through said relations.

Himiko was not the first to send emissaries to China. The Hou Han Shu ( 後漢書 )and archaeological evidence date Yayoi emissaries from the land of Na as early as 57 CE (Japan was called Wa 倭 at the time). Such investiture was important for a would-be ruler in Japan, especially when the fruits born from that relationship included iron ingots. As mentioned above, Yoshinogari possessed metal that surrounding hamlets did not. Imported metal was important, trade was needed, and as society shifted up Honshu, it was a sign of power. By the 2nd century AD, iron was in northeast Honshu thanks to military expansion and other kuni-rulers establishing contact with China and Korea.

It should also be noted that archaeological evidence of conquest in Japan at the time, meaning Gojoseon or other Korean groups did not conquer and become rulers that would lead to the line of Emperors. No evidence suggests Korean origin at all during the Yayoi or late Jomon.

Thus we return to Yayoi... or rather, Kofun period and Yamatai / Wa. Before, during, and after Himiko's reign, Yamatai chieftons sent emissaries to the three kingdoms- especially Paekche- and, thus, maintained contact and trade relations with the peninsula. In the mid to late 4th century, after many years of aggressive Koguryo activity thanks to a new wave of ‘martial kingship’ which the kings there embodied, Paekche was facing affront by both Koguryo and Silla. Yamatai had a big investment in Paekche and the tip of the Korean peninsula mainly due to the trade ports in Kaya, aka Mimana, where the majority of iron ingot shipments originated from; troops were even stationed there. So even as Yamatai was emerging as a full-fledged state, it was showing power by sending contingents of troops to aid Paekche in its defenses. This continued until the beginning of the 5th century when the Chinese monarchy once again dubbed Paekche’s king "The Great General Stabilizing the East and King of Paekche." Wa was regarded as a state on equal footing with both Silla and Paekche, a state worthy of receiving their respective princes for extended stays.

Pause to acknowledge the separate state emergence in the Koreas and Japan.

Yuryaku would be the first "King of Wa" (Wa no o 倭之王 ) if you believe his letters to China. In reality, he was one of five paramounts with whom the Liu Sung dynasty maintained diplomatic contacts with in the 5th century- last of the five to send an emissary, but third to receive recognition. Historians in the past, like Inou Mistusada in the '70s, viewed this time as one of unification with one ruler in the center and many peripheries; archaeological evidence and more recent history indicates multiple polities still existed with the "Great King" at its center. It seems like recent scholarship views Yuryaku as a politician of sorts as well, forging bonds through law and intermarriage with other polities in the region, but one who also faced ceaseless conflict from rivals. Keyholes tombs littered the plains in a display of power from various groups. (cont...)

Do you have any sources? I'm Korean and have always been told growing up that Japanese, Korean, and Manchurian (some Mongolian) are pretty much the same people. Would love to know more!