Altered states of consciousness induced by breathwork accompanied by music

No, it is only when you try to interpret them in today's context and assumed models which are quite different from the context/models in which they were written/practiced that it seems like mumbo-jumbo. They are more of an empirical science and it is up to you to study, practice and interpret them carefully.

For example; Mel Robin was a research scientist who got interested in Hatha Yoga and in true researcher fashion set about collecting/studying research papers and trying to map them to his practice of traditional Hatha Yoga. He wrote an excellent book A Handbook for Yogasana Teachers: The Incorporation of Neuroscience, Physiology, and Anatomy into the Practice (the 1st edition was called A Physiological Handbook for Teachers of Yogasana) with a huge reference section of research papers from various journals.

Another example; the neuroscientist James Austin wrote a mammoth book Zen and the Brain: Toward an Understanding of Meditation and Consciousness where he tried to map his knowledge of neuroscience to his experiences from Zen meditation practice.

Empirical practices which have survived for centuries and across civilizations are usually "scientifically" valid and it is up to us to map them to modern scientific concepts.