The Characteristics of the Gusuku Period and the Rise of Aji Chieftains
With the approach of the 12th century the long Shell Mound Period ended and Gusuku started to be constructed throughout the islands, thus the Ryukyus entered the Gusuku Period.
There are four things that distinguish this period. The first feature is that the people who had been living in low-lying areas near the coast again moved inland and built villages on limestone plateaus and cliffs. The second is that sacred groves called Utaki were constructed within the villages to pray to guardian spirits and grain cultivation (paddy rice, wheat, millet) became the focus of agriculture activity. The third feature is related to the development of agriculture and is regarded as the actual start of the use of metal agricultural tools. The fourth feature is the beginning of overseas trade at the same time that the Ryukyu Islands began to create a common cultural sphere. This is evidenced by the existence of Sueki ware in the Amami Islands region and from excavated Chinese ceramics.

Important in the understanding of how Gusuku developed is the appearance of Aji regional chieftains. This period saw the emergence of villages centered on blood relations. As an agricultural lifestyle developed, there was the necessity to conduct a variety of communal works, from the clearing of land to cultivation, planting and harvest. To achieve this, people helped each other and at the same time village helped village as well. Mutual ties were established. The villages deepened their mutual ties and rulers fulfilling leadership roles appeared. As the agrarian society was being constructed, the 13th century began and consolidating the interests of the villages lead to the rise of individuals who occupied ruling positions. These leaders came to be called Aji or Anji.

As political leaders, the Aji levied taxes and carried out the implementation of ceremonies and rites. Prosperous trade was conducted between each of the regions, including countries overseas. This resulted in the increased strength of the Aji chieftains in possession of good harbors such as those in Urasoe, Yomitan, Nakagusuku, Katsuren, Sashiki and Nakijin.