The practice of Buddhism does come from Himduism. But it was said Lao people have observe, practice the calling of the souls/spirits long before the teaching of the Buddha made its way into SEA regions. It's borderline voodoo/black magic, its belief that su kuan (baci) invoke the 32 organs of the human body consider as spirits. It's part of keeping balance and harmony with one self and the community and the after life.