In 1609, Japan invaded the Ryukyu Kingdom, and trade with foreign countries was prohibited.

Ryukyu Kingdom is the ancient name for what is presently known as Okinawa, Japan.

The castle now contains the remains of several kings of the Ryukyu Kingdom.

Historically, the Kerama Island group was a part of the Ryukyu Kingdom.

Okinawan people have spoken Japanese since the Ryukyu Kingdom joined Japan.

They were used as the official names during the early era of the Ryukyu Kingdom.

Japanese hegemony began to increase in the 17th century, and in 1879 the Ryukyu Kingdom was annexed by Japan.

The Ryukyu Kingdom retained autonomy until 1879, when it was invaded and annexed by Japan.

These sites, and Chūzan as a whole, would continue to form the center of the Ryukyu Kingdom until its abolition.

In other words, the Ryukyu Kingdom was then recognized as a han.