The Kofun period, ranging from approximately 300 to 538 CE, marks a critical stage in Japan's historical and cultural development. This era is characterized by the emergence of keyhole-shaped burial mounds, known as "kofun," and is considered the earliest period of recorded history in Japan. The Yamato clan rose to power during this time, particularly in southwestern Japan, where they centralized political authority and began developing a structured administration influenced by Chinese models. The period was also marked by the autonomy of various local powers like Kibi and Izumo, but by the 6th century, the Yamato clans began to assert dominance over southern Japan.^[19]

During this time, society was led by powerful clans (gōzoku), each headed by a patriarch who performed sacred rituals for the welfare of the clan. The royal line that controlled the Yamato court was at its peak, and clan leaders were awarded "kabane," hereditary titles that indicated rank and political standing. The Yamato polity was not a singular rule; other regional chieftainships, such as Kibi, were in close contention for power during the first half of the Kofun period.

Cultural influences flowed between Japan, China, and the Korean Peninsula,^[20] with evidence like wall decorations and Japanese-style armor found in Korean burial mounds. Buddhism and the Chinese writing system were introduced to Japan from Baekje near the end of the Kofun period. Despite the centralizing efforts of the Yamato, other powerful clans like the Soga, Katsuragi, Heguri, and Koze played pivotal roles in governance and military activities.

Territorially, the Yamato expanded their influence, and several frontiers were recognized during this period. Legends such as that of Prince Yamato Takeru suggest the existence of rival entities and battlegrounds in regions like Kyūshū and Izumo. The period also saw an influx of immigrants from China and Korea, with significant contributions to culture, governance, and the economy. Clans like the Hata and Yamato-Aya, comprised of Chinese immigrants, had considerable influence, including in financial and administrative roles.