These banknotes were printed in the People’s Republic of China for use in South Viet Name after liberation by the National Liberation Front. They were never issued, because they were captured during a joint US / South Viet Nam military operation into Cambodia. Except for #R1 and R2, relatively few survived in uncirculated condition. Their date was recently changed from 1963 to 1968 after a Chinese book described the notes as being printed in 1968. This indicates they were intended for the second money conversion in South View Nam, which never happened.

Source Come From: https://en.wikipedia.org/wiki/Central_Bank_of_the_Republic_of_China_(Taiwan)