Can anyone please explain about the Nationalist movement in Indo - China?
It is complex and involved a number of movements both non-violent and violent. The countries of South East Asia existed before the French and others drew their boundaries.
I took a tour through the "Hanoi Hilton" that housed American POWs in Hanoi. It was also used by the French for Vietnamese political prisoners since the 1880s.
Vietnam existed from about 3000 BCE. There have been many invasions. The Chinese Invasion in about 1406 is well documented.
The Chinese were expelled by 1428. The Le Dynasty was established.
I haven't read all of this but it may be helpful. Vietnam has a long history of resistance.