Which invention helped the Chinese solve the problem of needeing more money for trade?

The invention of paper currency in China helped solve the problem of needing more money for trade. Initially introduced during the Tang Dynasty and later developed further during the Song Dynasty, paper money provided a more convenient and lightweight alternative to heavy metal coins. This innovation facilitated trade by simplifying transactions and increasing the efficiency of commerce across regions. As a result, it significantly boosted economic activity and trade networks in China.