The Yamato court's supremacy was challenged during the Kofun period by other polities centered in various parts of Japan.
At the era of Prince Shōtoku in the early 7th century, a new constitution was prescribed for Japan based on the Chinese model.
After the fall of Baekje (660 AD), the Yamato government sent envoys directly to the Chinese court, from which they obtained a great wealth of Confucian philosophical and social structure.
In addition to ethics and government, they also adopted the Chinese calendar and many of its religious practices, including Confucianism and Taoism (Japanese: Onmyo).
In the centuries prior to the beginning of the Yamato period, elements of the Northeast Asian and Chinese civilizations had been introduced to the Japanese archipelago in waves of migration.
Some describe the "mysterious century" as a time of internecine warfare as various local monarchies competed for hegemony on Kyūshū and Honshū.
[5] Kofun (古墳, "old tomb") are burial mounds which were built for the people of the ruling class during the 3rd to 7th centuries.
The Kofun period takes its name from these distinctive earthen mounds which are associated with the rich funerary rituals of the time.
A distinct style is the keyhole kofun (前方後円墳 zenpō kōen fun), with its square front and round back.
By the late Kofun period, the distinctive burial chambers, originally used by the ruling elite, were also built for commoners.
Kofun are also classified according to whether the entrance to the stone burial chamber is vertical (縦穴 tate-ana) or horizontal (横穴 yoko-ana).
Yamato links to the mainland and the Liu Song dynasty in 425 and 478 were facilitated by the maritime knowledge and diplomatic connections of China and the Three Kingdoms of the Korean peninsula, especially Baekje.
The Yamato polity, which emerged by the late 5th century, was distinguished by powerful great clans or extended families, including their dependants.
According to Nihon Shoki, Mahāyāna Buddhism (大乗仏教, Daijō Bukkyō) was officially introduced to the Yamato court through Baekje in 552, while it is widely recognized Buddhism was introduced in 538 based on the biography of Prince Shōtoku (Jōgū Shōtoku Hōō Teisetsu) and the record of Gangō-ji (Gangōji Garan Engi).
Nihon Shoki records that when Emperor Kinmei discussed about the acceptance of this new foreign religion, Soga no Iname expressed his support while Mononobe no Okoshi and Nakatomi no Kamako (later the Fujiwara clan) opposed not on religious grounds, but more so as the results of feelings of nationalism and a degree of xenophobia.
With the dawn of the Asuka period, the use of elaborate kofun tombs by the imperial family and other elite fell out of use because of prevailing new Buddhist beliefs, which put greater emphasis on the transience of human life.
Asuka period mid-seventh century, the agricultural lands had grown to a substantial public domain, subject to the central policy.