Generally, the skulls of hoofed animals such as horses, cows and sheep are used to make three-boundary cards, among which sika deer is the best. The skull of sika deer is hard and thick, especially some bones on the top of the head show a little moisture.

Sanjie card was originally cut from animal skulls. It is the most precious and legal Sanjie card, and it is also the most played Sanjie card in the world today, that is, Deer Sanjie card. Because of its three roads, it is called three streets. In Tibetan Buddhism, animal bones are used to make artifacts. It is said that Sanjie is a place where deer gather aura, so it is extremely unique.