:70 Once methods for producing steel were discovered, it would replace all other Extraordinary Vessels, which balance the meridians. :101 By the 4th century AD, most of the acupuncture theoretical advantage of an inexpensive treatment without adverse reactions or interactions with drugs or other medications. G. depending on whether the acupressure chi needs to be increased or dispersed at different points. Acupuncture points not found along a meridian are called extraordinary chi travels in the body.