The main currency in the CarryTrade is Yen, because at that time the interest rate of Yen was very low. And many operations of Carry Trade were marked by AUD and NZD.
Due to its extremely low interest rate, Japenes Yen became the main currency for CarryTrade, and the object currency was the Australian dollar and the New Zealand dollar.
At that time, the main currency for Carrytrade was Yen as its exchange rates were pretty low then. Many bids for those trades were Australian dollar and New Zealand dollar.