It is believed that it was introduced by a Tibetan saint known as Dupthob Thangtong Gyalpo. He is revered by the Bhutanese people as a master engineer for his skill in casting iron chains and erecting them as bridges over gorges. He is supposed to have built eight suspension bridges in Bhutan.
You can still see one of the bridges crossing over the Paro Chu, on the road from Paro to Thimphu, and linking the highway to the famous Tachog lhakhang. The remains of another bridge can be viewed at the National Museum in Paro.
While blacksmithing is almost a dying art, you can still find the original Tibetan settlers in Trashigang practicing this skill.