1 Cash - Songyuan Tongbao, iron

Issued under Emperor Taizu of Song during the dynasty's first decade, the Songyuan Tongbao was among the earliest coinages of a regime that would go on to become the most prolific producer of cast bronze coinage in Chinese history. Iron cash were struck regionally when copper supplies ran short or when local economies required supplemental currency — they circulated at face value alongside bronze issues but were universally regarded as inferior. Hoarding of copper and the chronic metal shortages of the early Song fiscal apparatus made iron an unavoidable expedient from the outset.