This form of lat money (= "market money") exists in three varieties. The oldest pieces are smooth silver ingots from good silver with three little stamps on the upper side. They circulated from the 14th century in Lan Chang, an old kingdom in the north of todays Laos. In the 16th century, Lan Chang proceeded to issued "tiger tongues." They were not smooth any more but bore warts on the upper side. Those tiger tongues did not bear stamps any more. In 1707 Lan Chang split into several smaller kingdoms. One of them was Luang Prabang. It adopted the tiger tongues, and additionally introduced bronze ingots with a smooth surface. These are called "boat money" or "canoe money" today.