Today was the first trading day after the National Day Holiday, and the Renminbi hit its lowest level against the US dollar in six years.

The People's Bank of China set the Renminbi's midpoint rate at 6.7008 per dollar on Monday, 230 basis points below the rate set on September 30, the last trading day before the holiday.

Experts say the Renminbi's depreciation is the result of a strengthening US dollar, which was caused by the weakening of the British pound.

The British pound has been in decline since Prime Minister Teresa May announced last week that the country will start its exit from the European Union in March 2017. Investors reacted by selling their pounds and buying dollars.

"The plunging British pounds has lead to a jump of US dollars and that made the Renminbi depreciate," said Wan Zhao, senior analyst, China Merchants Bank.

"The Renminbi's daily midpoint fixing was weakend to 6.7 per dollar and as the People's Bank of China hints that it doesn't want to defend the 6.7 threshold. As the US dollar index continues to climb, there is more space for the yuan to depreciate."

The US dollar has been on the rise since the middle of September.