Final answer:
Liu Bang, the first emperor of the Han dynasty in China, introduced a unified currency system called Ban Liang, which brought economic stability and facilitated trade.
Step-by-step explanation:
The emperor who established a unified currency system was Liu Bang. Liu Bang was the founder of the Han dynasty in China and implemented various reforms, including the introduction of a standard currency system known as the Ban Liang. This currency system played a crucial role in promoting trade and economic stability throughout the empire. With the Ban Liang, trade became more efficient, and it helped in the expansion and stability of the Han dynasty.
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