In the Plain of Jars area, the most numerous peoples are the lowland Lao, Hmong, Black Tai, and Kammu. The Puan people, the Lao of the Plain of Jars, are a group of lowland Lao whose language and customs are slightly different than the Lao Loom in other regions. However, in modern times, after frequent population movements in and out of the area, they have been assimilated into the mainstream Lao group, and their language, for all practical purposes, approximates the common Lao tongue, except for some vocabulary and tonal differences.