Horserider Theory

The Horserider Theory is a theory of the origins of Japan. It suggests that northern Asian 'horse-riders' influenced Japan in the 4th and 5th centuries CE. These horse-riders came from North Asia and the Korean peninsula. They conquered indigenous tribes in Japan. This led to the formation of the Yamato state. The theory is based on horse trappings found in Japanese tombs from the Kofun Period.

The Horse-Rider Theory was proposed by Egami Namio in 1948.

Overview
Fifth-century tombs from the Middle Kofun period (Kofun III) are large. They have many moats and deposits of iron tools and weapons. Fewer bronze mirrors are found, and more tools appear. This shows a change in elite status symbols.

The region saw changes in territory. Small political groups from the Early Kofun period joined under the Kawachi Court. This made the first regional political group called "Yamato." Its base was in Kawachi. Many think Yamato started outside the Kinai region, likely from riders from Korea.

There is evidence of Korean influence on Japanese culture during this period. Archaeology and genetics show this influence. The Japanese Imperial family mixed with Koreans. Japan had relations with the Korean state of Baekje. Many historically known immigrants known as Toraijin arrived from Korea. Japan also traded with China. These interactions show cultural exchange in the region.

The idea of a Korean force conquering Japan is debated. The Nihon Shoki, an 8th-century source, suggests a Japanese presence in Korea. This is now seen as unlikely. The influx of Korean goods and ideas into Japan did not result in a clear cultural change. This suggests a different form of cultural exchange.

Criticism
Japanese historians challenge the Horse-Rider Theory. They point out issues with its timeline and evidence. They question the assumption that foreign goods mean military conquest. Korean historians argue for a cultural shift. They use changes in tombs and political structures as evidence. They also point to linguistic and mythological evidence.

Many Japanese archaeologists challenge the theory. They say horse items appear too late to explain the early fifth-century tombs. Historians have other concerns. They question the focus on Central Asian people and the interpretation of history.

Others think the theory overemphasizes sudden change. They think slow cultural interactions make more sense. Some believe the state formed through cultural changes, not just one conquest event. Other ideas say the fifth-century changes came from conflicts with Kyushu. This led to new trade with Korea.

Many historians propose interconnectedness between peoples across the Korean Straits without invasion or conquest. Migrations from Korea to Japan happened around 300 BCE. These migrations brought cultural and technological changes to Japan. This shows a cultural connection rather than separation between Korea and Japan.