Which countries put square holes in their coins on purpose?

Answer 1

The practice of putting holes, specifically square holes, in currency originated in China. Holes were typically placed in 方孔錢 (fang kong qian) or cash, as it is refereed to in English, before China started using the recognizable round coin shape. Instead, cash was in the shape of a knife or a small spade prior to the use of round coins. The first known use of square holes in round cash as been dated to as early as 378 BCE.

Since many countries in East Asia adopted Chinese currency systems because for their presence in the Chinese cultural sphere, these countries likewise used square-holed coins for at least some of their currency usage. These include Japan, Korea, and Vietnam. Some other countries, such as Brunei, were known to use Chinese currency before establishing their own systems. That being said, most of Southeast Asia either developed their own early currency systems or did not have a currency prior to European exposure, relying on barter.