Commodities are often separated from other asset classes because they are inversely correlated with stocks, bonds and currencies. In the current environment of low commodity values, we see stocks and bonds near their highs, as well as currencies—specifically the US dollar. But commodities and currencies have a much closer relationship than it appears.

The US dollar is one of the biggest influences on commodities. As the dollar rises in value, commodities drop. This happens because investors view the dollar as a safe haven asset when inflation is low. Commodities don’t generate profits—instead they maintain value outside of international currency fluctuations making them attractive during periods of high inflation when currency values are dropping.

However, there are some currencies that are closely tied to commodity prices. Countries whose economies are closely tied to exporting commodities will have a currency that rises or falls alongside the worldwide demand for the underlying commodity. This correlation makes investing in these assets more volatile than others, and investors should be aware of the relationships.

While emerging market economies often have their currencies tied to major commodity exports, there are some developed markets whose currency is similarly affected—as the worldwide value of that commodity fluctuates, so too does their currency. Currency trades can often be set by looking at these relationships as well.

Canada is one of the world’s largest exporters of oil, which makes which makes the Canadian dollar sensitive to changes in oil values. A quarter of Canada’s exports comes from the oil sector making it a heavy influence on the value of their currency. The Canadian dollar has fallen, along with oil prices, over the past year hurting Canadian imports and negatively impacting the US economy. The end result is that low oil prices means fewer US dollars in circulation causing the demand for the dollar to rise and the demand for the Canadian dollar to fall further.

Australia is responsible for about a third of global iron core production making its economy sensitive to changes in the value of iron and steel. China had been the single largest importer of iron to fuel its booming economy—but with China’s sudden decline, the demand for industrial commodities is at all-time lows. The lack of demand has put pressure on the Australian dollar and caused it to fall precipitously over the past year.

Copper is Peru’s number one export by value resulting in a strong positive correlation between copper prices and the Peruvian sol. The South American country’s economy is closely tied to the health of the global economy as well since copper is generally referred to as a global economic barometer. As with other commodities, China’s lack of demand has hurt copper prices causing the Peruvian sol to drop in the past year.

There are several other countries whose currency is tied to a commodity, such as the Russian ruble and oil, and the New Zealand kiwi and gold. It’s important to note economic relationships in countries who are heavily commodity dependent. A drop in the economy of an importing country will almost certainly be bad news for the exporting country. Until China’s role as a commodity-hungry economy is replaced, these countries (and their currencies) will face continuous negative pressure for the foreseeable future.