Gankyil means "wheel of joy". It is somewhat similar to the tàijítú (太极图) of Chinese philosophy, better known in the west as the yin-yang-symbol. The difference is that the gankyil has 3 or four swirls, as opposed to the two of the tàijítú.
It is often described as representing the three sacred jewels: the Buddha, the Dharma, and the Sangha.
In the older Bon religion it denotes the three principal terma ("hidden teachings"); the "Northern Treasure" the "Central Treasure" and the "Southern Treasure".