The answer is a reliance on oil, which hit nine-month highs last week on turmoil in Iraq, raising concern about the impact on Asia's economies.
The geopolitical risks from an escalating crisis in Iraq are hard to predict, but the impact on currency markets from the rise in oil is clear, analysts at Mizuho Corporate Bank said in a research note.
"Unsurprisingly, currencies of the largest oil importers, such as India and Korea (the third and fourth largest global crude importers respectively) have taken a significant initial hit," they added.
The Indian rupee last week hit its lowest level against the U.S. dollar since late April, while the South Korean won was pushed off a six-year high around 1,015 per dollar.
Asia is heavily dependent on oil imports and according to the U.S. Energy Information Administration, seven of the world's top 15 net oil importers are from the region. China, Japan, India and South Korea are all in the top five, with the U.S. leading the list.
Brent crude oil prices have risen more than 5 percent over the past two weeks and were holding near $115 a barrel on Friday.
Mizuho Corporate Bank said India was the most vulnerable Asian economy to higher oil prices given that the Indian rupee has depreciated over 30 percent since the start of 2008. It is followed by the Philippines, Korea, Thailand and Indonesia, Mizuho said.
"What's more, fuel subsidies in India, Indonesia and Thailand mean vulnerabilities to oil price shocks are in reality even more pronounced," Mizuho analysts said.