It's only known for sure that the district acquired its name after the ROC government took possession of the island at the end of the Second World War, and that its area shrank after martial law was repealed in 1987.
現在已經無法考查，只知道這個名詞是在國民政府接收台灣以後才產生的，並曾在一九八七年解嚴後縮小部分範圍。