The construction of
gusuku began throughout the
Ryukyu Islands during the Gusuku Period (1187–1314) with the rise of chieftains and feudal lords called
Aji at the approach of the 12th century. During this period, people who had been living in coastlines along low-lying areas had moved to higher ground to build villages inland. Agriculture, such as
paddy rice,
wheat and
millet, was developed further during this period. Certain groves within these villages were designated as sacred grounds, called
utaki, for praying to guardian spirits of cultivation. Overseas trading was also opened when the Ryukyu Islands began to create a common culture. The existence of Sueki ware and Chinese ceramics excavated in the
Amami Islands region is considered as strong evidence of its cultural development. At the beginning of the 13th century, a steady rise in the interests of the villages saw the emergence of chieftains who were called
Aji or
Anji and who occupied political positions within these villages. The
aji mainly oversaw taxes and conducted religious rites along with
Noro priestesses. Trade became more developed and persuaded the
aji to gain possession of good harbors like Naha, Yomitan, Itoman, Katsuren, Sashiki, and Unten. The
Sanzan Period (1314–1429) began when the regional
aji dealt with struggles to defend their domains as their powers increased.
Okinawa Island was eventually divided between three competing kingdoms:
Hokuzan in the north with its capital at
Nakijin Castle,
Chūzan in the central area with its capital at
Urasoe Castle, and
Nanzan in the south with its capital at
Nanzan Castle. The three kingdoms competed for territory in the
Okinawa Islands and recognition from
Ming China. The Sanzan Period ended in 1429 when King
Shō Hashi conquered the three kingdoms and was recognized by the Chinese Emperor as "King of Ryukyu". The newly formed
Ryukyu Kingdom, with its capital at
Shuri Castle, then conquered neighboring islands, starting with the Amami Islands to the north by the mid 15th century and the
Sakishima Islands by 1500. Gusuku continued to be built during this period, the most notable being
Nakagusuku Castle and
Yarazamori Castle. A significant change in status for the kingdom happened in 1609 with the
invasion of Ryukyu by
Satsuma Domain of
Japan. Satsuma destroyed both Nakijin Castle and Urasoe Castle, as well as capturing Shuri Castle, during the war. Satsuma won the war, vassalized the Ryukyu Kingdom, and annexed the Amami Islands. Gusuku-building stopped after the 17th century. After
Japan annexed Ryukyu in 1879, some gusuku were used by the
Imperial Japanese Army. During the
Battle of Okinawa in
World War II, most of the Gusuku used by the Japanese military, especially Shuri Castle, were damaged or destroyed. Shuri Castle was rebuilt during the 1990s, and in 2000 it and a number of gusuku and other related sites were added to the UNESCO World Heritage Site list. ==Preservation==