The Qidan was one of the nomadic tribes that had encroached on China since before the Tang. They ruled Northern China from 916-1125 and were a constant threat to the Song. 
These nomadic people were excellent horsemen and brave warriors. They had their own written language, but all their coins were cast with Chinese characters. The Qidan still used a natural economy right up to the end of their dynasty, and exchanges and payments were denominated in terms of livestock (Peng p. 458-459).
Liao coins were cast with a reddish copper alloy. They were crude, unevenly cast and with poor calligraphy.
The Liao dynasty did not produce many coins, only about ½  a million pr. year, it is therefore likely that Song coins were still in use during the Liao dynasty (Ren p. 87).