What are you talking about What you did is the fillintheblank question Gusuku  often refers to castles or fortresses in  that feature stone walls  And your answer is the Ryukyu Islands Thats wrong in the sense that we wouldnt say We speak Germanic when we actually speak English Castles or fortresses that feature stone walls are typical of Okinawa Applying the term to other island groups is highly problematic to say the least  Narratives about gusuku are truly chaotic No wonder you dont understand the situation correctly No one can define the meaning of gusuku which reminds me of family resemblance Whats why I avoided the A is B definition and used A often refers to B in the article Explaining many conflicting theories as I did in the article is confusing So I present just one hypothesis which I personally support  The word gusuku originally meant stone walls that say partitioned agricultural fields In other words the word gusuku was not associated with castles This meaning survives in Yaeyama  There has been a long tradition of mountain cult At first the word gusuku was not associated with mountain cult  In Amami medieval mountain fortifications that are typical of mainland Japan were constructed probably in response to Rykys repeated invasions At this stage the word gusuku was not associated with these mountain fortifications  In Okinawa some sacred mountains were later fortified with stone walls One consequence of the fusion of mountain cult and fortification was the association of the word gusuku with mountain cult andor fortification The association of gusuku with stonework was weakened but anyway Okinawas castles and fortresses had stone walls  Ryky finally conquered Amami and introduced the noro ritual system to Amami The new meanings of gusuku  related to mountain cult  fortification were also introduced to Amami Most of the former medieval mountain fortifications were abandoned but some were transformed into sacred places and given the name of gusuku even though they lacked stone walls Some people of Amami might have interpreted the word gusuku as fortifications regardless of whether they had stone walls Others reinterpreted the word as a sacred place regardless of whether it had stone walls For this reason some gusuku are on sand dunes on cliff edges and in caves  Archaeologists of Okinawa Prefecture reused the word gusuku as a technical term yet another meaning This was the source of confusion They referred to Okinawas castles and fortresses that feature stone walls as gusuku They met fierce oppositions from folklorists because their use of gusuku was not grounded in peoples actual usages  Some archaeologists of Okinawa Prefecture attempted to extend the gusukuasfortifications framework to Amami Miyako and Yaeyama regardless of whether local people referred to the target as gusuku The remains of human settlements of Yaeyama are not called gusuku by local people either They met fierce oppositions not only from folklorists but also from fellow archaeologists  It is convenient to consider a dichotomy between inductive and deductive reasoning Linguists folklorists and ethnologists base their arguments on peoples actual usages and try to infer a generalized conclusion from them By contrast archaeologists often define a term independently of peoples actual usages and apply it to those which meet the definition Due to lack of written materials archaeologists need to name archaeological findings by themselves So they naturally clash with scholars from other disciplines  It is important to note that the gusukuasfortifications framework thats what the lead sentence says is no longer supported in the archaeology of the Amami Islands The renaming of socalled Uragami Gusuku was a symbolic event A gusuku is a gusuku only because people refer to it as such Its not because the referent meets some definition In Amami gusuku as a technical term is dead long live gusuku as to peoples actual usages