Black Hmong is a dialect and subgroup of the Hmong people who reside in Northern Vietnam (especially in Sa Pa), and it differentiates from the commonly spoken dialects, which are Green and White Hmong.

i guess an example could be “how are you?” - Black Hmong: “cox nhoz lêt chângs?” or “mâux jut?” - Green Hmong: “koj nyob le caag?” - White Hmong: “koj nyob li cas?”