The Vietnamese word "nha phiến" refers to "opium," which is a powerful narcotic derived from the opium poppy. In historical contexts, particularly in Vietnam, "nha phiến" is often associated with the Opium Wars, which were conflicts that took place in the 19th century primarily between China and Western powers, over trade, particularly the opium trade.
Understanding "nha phiến" is important for grasping historical discussions about drug trade, especially in Vietnamese and broader Asian contexts.