Answer:
The Yamato rulers began calling themselves emperors of Japan in the 7th century AD, as a way to legitimize their rule and gain greater influence and authority. This move was partly influenced by China, which had an emperor, and the Yamato rulers wanted to be seen as equal in rank and status to their powerful neighbor. It was also a way to distinguish themselves from other regional rulers in Japan who did not claim the title of emperor. Over time, the imperial court in Japan became more established and the emperor became a symbol of unity and stability in the country.
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