The coinage was invented in India around 6th-7th century B.C. and it was the 'Jana padas' that issued such coins for the first time. These coins were made of silver and contained only symbols. The symbols were marked on them by punching method without any legends. Some of the Jana padas which were scattered around the country issued such coins of varying weights, sizes and symbols. Magadha started as a Jana pada and issued local Jana pada type of coins first. Later it conquered adjacent Jana padas to become an imperial power and issued first national currency of uniform weight of 3.4 grams (32 ratties) with five symbols that included sun and six armed marks on the obverse side and these coins came to be known as Imperial type of punch marked coins. Reverses were blank on these coins except for some marks known as banker's marks on them.