sentences:  Since the Three Kingdoms period, silk was considered to be one of the most highly valued medium of exchange.As in modern times Xin dynasty era "hwacheon" (貨泉, 화천) cash have been unearthed in tombs in modern Korea there is minor evidence that these coins might've been used for the international trade of the time.In 2018 Wu Zhu (五銖, 오수) cash coins, known as "oshujeon" in Korea, were unearthed in the North Gyeongsang province further confirming an ancient trade relation with China.