But then came the sanctions.
As negotiations over Iran's nuclear programme eached a stalemate in recent years, the US and the European Union intensified their sanctions against Iran's energy and banking sectors.
The sanctions have resulted in two major financial hiccups in the past 18 months.
In the latter half of 2011, the Dubai-based Noor Islamic Bank, under pressure from the US Treasury, stopped clearing Iran's oil money. The Wall Street Journal at the time reported that the bank was responsible for settling up to 60% of Iran's then $100bn (£62bn) oil revenue.
The knock-on effect was a major drop in the rial's value as Iran's central bank fell short on US dollars, before finding alternative routes for bringing its petrodollars home.
Soon after, on New Year's Eve, President Barack Obama signed into law sanctions against any entity which dealt with the Central Bank of Iran, a measure which put off many financial institutions from doing business with Iran under the fear of being locked out of the US market.
Iran's major Asian buyers of crude that were paying into the bank also had to cut up to 20% of their imports in order to win exemptions from these sanctions.
This, plus the EU embargo on Iranian oil which started in July, have cut Iran's oil income by at least 45%, hence the current crisis in hard currency.
