If it is argued that these mirrors were produced after 280, it is difficult to understand why the era inscribed in them was between 235 and 244 during the Three Kingdom Period (China).
これらを280年以降の製造と考えると、紀年鏡に記される年号が何ゆえに三国時代(中国)の235年から244年に集中しているのか、整合的な理解が難しい。