The Hmong were situated in and around the PDJ in Laos. In places like Padong, Sam Thong, Long Tieng. VP had his HQ's in Long Tieng. Other tribes in Laos I was familiar with are the Khmu, the karen and the Akha. All lived in different regions of Laos.
With Vietnam, your probably talking about the Montagnards. The Hmong and montagnards were two distinct people with different customs and languages.
Although Montanans can refer to around 30 or more mountainous tribes in Southeast Asia. It's a French word that means Mountain dwellers
Although most refer to the Vietnam Was as one war, it wasn't. There was the war in Northern Laos, the one along the Ho Chi Minh Trail in Laos and Cambodia, the one in South Vietnam and the one in Cambodia. All fought differently using different tactics and equipment. But it was Vietnam that had most of the U.S. troops. There were 122 of us in Laos with Project 404, MEDTC in Cambodia had around 70 if I remember right. At its height there were 536,000 U.S. troops in South Vietnam.
Troop Strength in South Vietnam
1950 65 US Military MAAG-INDOCHINA
1951 128 US Military
1952 128 US Military
1953 128 US Military
1954 342 US Military MAAG-INDOCHINA BECOMES MAAG VIETNAM
1955 342 US Military
1956 342 US Military
1957 692 US Military
1958 692 US Military
1959 760 US Military
1960 890 US Military
1961 3,205 US MILITARY
1962 11,300 US MILITARY MACV established
1963 16,700 US MILITARY
1964 23,300 US MILITARY MAAG-Vietnam disbanded, MACV Absorbs all its functions
1965 184,300 US Military 22,420 Allied Forces
1966 385,300 US Military 52,500 Allied Forces
1967 485,600 US Military 59,300 Allied Forces
1968 536,100 US Military 65,600 Allied Forces
1969 475,200 US Military 70,300 Allied Forces
1970 334,600 US Military 67,700 Allied Forces
1971 156,800 US Military 53,900 Allied Forces
1972 24,200 US Military 35,500 Allied Forces
1973 50 US Military No Allied Forces US Military attached to the DAO*
1974 50 US Military No Allied Forces US Military attached to the DAO*
*Does not count Marine Security Guards for the Embassy and multitude Counsels located around South Vietnam.
Yearly totals are on the 31st of December of each Year. Allied
Forces include Australia, South Korea, Thailand, New Zealand, Philippines and 30 advisers from Taiwan.
1950/51 Figures from Biography of H.S. Truman
1952-1960 Figures from Biography of D.D. Eisenhower
1961-1974 Figures from Col Summers Vietnam Almanac