Yes, it's Chinese, earliest documentation is around 3000 BC (the Yellow Emperor's Classic of Internal Medicine). 2 alternative explanations: Chinese and Western.
Chinese: Disease is caused by imbalance of life force (qi) which flows around the body in channels called meridians. Along the meridians are acupuncture points. Some are Yin, some are Yang, and the points counterbalance each other. Disease is caused by an excess of one or the other. Needles placed in relevant points allow the excess Yin or Yang to escape, thus restoring the balance of the Qi.
Western: Trigger points are nodes of nerve hyperactivity, and are found all over the body. Stimulation of these nodes may affect deeper organs via a skin/nerve reflex; in addition disease in deeper organs may give rise to skin tenderness.
Mechanism of acupuncture pain relief is not clear; most likely acts through A delta nerve fibres to activate the Pain Gate. Whether it REALLY works or not is the subject of a great deal of research at the moment.