Since several centuries, the intrinsic value of gold was recognized. Hence, many countries followed gold standard for the valuation of their currencies and guaranteed that; on demand, they shall pay their currency value in shape of gold.
After great depression in 1930-33, there was reluctance in accepting the currency of other nations due to mismatch of “reserve gold stock” with their Central Banks. Hence, the international trade and financial transactions were severely affected.
Read more on financialexpress.com