The rial was first introduced as the currency in Iran in 1798 as a coin. Back then it was worth 1250 dinars.
Then in 1825 the rial ceased to be issued. The kran of 1000 dinars was then issued as part of a decimal system. The rial replaced the kran at par in 1932, although it was divided into one hundred (new) dinars.
When talking money in Iran you may hear the term “toman”.
The toman is an old term but is no longer an official currency. However it is is still used on a daily basis in Iran and it refers to the amount of ten rials.
The rial (ISO 4217 code IRR) is the currency of Iran. It is subdivided into 100 dinar but, because of the very low current value of the rial, no fraction of the rial is used in accounting.
Although the "toman" is no longer an official unit of Iranian currency, Iranians commonly express amounts of money and prices of goods in "tomans."
For this purpose, one "toman" equals 10 rials. Despite this usage, amounts of money and prices of goods are virtually always written in rials.
For example, the sign next to a loaf of bread in a store would state the price in rials, e.g., "200 Rials," even though the clerk, if asked, would say that the bread costs "20 tomans."
There is no official symbol for the currency but the Iranian standard ISIRI 820 defined a symbol for use on typewriters (mentioning that it is an invention of the standards committee itself) and the two Iranian standards ISIRI 2900 and ISIRI 3342 define a character code to be used for it.