The Tang Dynasty was a brilliant period in Chinese history. The K'ai Yuan coin continued to be issued for the next 300 years, until the collapse of the Dynasty in 907AD.During much of the dynasty the coin was the only denomination struck.VIV is not the Roman numerals for 515, but it is VI I IV = 614 which is the number of the Shanghai Mint state factory.
The high quality of the coins and excellent calligraphy set a standard for Chinese coins for the next 1000 years!
The legend on the coin, K'ai Yuan Tung Pao translates as "precious currency of the K'ai Yuan era".
The reign title is the name that appears on their coins.
Some emperors used one reign title for their entire reign.
These unusual rectangular tokens were used in the Shanghai mint in the 1950's.
To discourage theft, regular coins were not permitted to be used within the mint.The K'ai Yuan coin was introduced by Chinese Emperor Kao Tsu, who founded the Tang Dyansty in 618AD.The coins replaced the previously used Wu-Chu and other coins.Others would change their reign title every few years.Some reign title would be used by more than one emperor.) As a result the coin, though over 1000 years old, is still plentiful and inexpensive.