In Okinawa, dictatorships began to arise in various areas from around the twelfth century, and castle-like buildings called "Gusuku" were constructed. However, these buildings were not like Himeji Castle, which is also registered as a World Heritage Site, but more like a fort. Gusuku were also treated as sacred sites under local religious belief. When the 14th century came along, each area was unified into three counties and the unified Kingdom of Ryukyu was finally established in 1429. In line with this, the symbol of the Kingdom "Shuri-jo Castle" became the sole Gusuku.