Of the gifts of the magi, in the modern world, we’re most familiar with gold. It’s an easy seasonal joke to say something along the lines of, “What’s the other stuff for?” Wikipedia says they were used in embalming and to mask the smell from funeral pyres. Incense. That sounds about right.
From plants grown in East Africa and Arabia, frankincense and myrrh are useful items in the Chinese Materia Medica, particularly for pain relief and to promote healing. Ru Xiang and Mo Yao (frankincense and myrrh, respectively) both invigorate the blood, reduce swelling, and alleviate pain. While they both address pain of the chest and abdomen as well as carbuncles, swellings and traumatic injuries, ru xiang also relaxes the sinews. It is used for rigidity and spasms, while mo yao is better for severe, stabbing, pain. In Chinese medicine, this is stasis pain, and mo yao is also indicated for immobile abdominal masses. Topically, they are both used to promote healing. Ru Xiang is used for traumatic injury and is said to “generate flesh,” while Mo Yao is better for chronic, nonhealing sores.
In clinical research, ru xiang treated tuberculosis in rats. Mo yao lowered serum cholesterol and prevented plaque formation in rabbits with diet-induced hypercholesterolemia. It also was shown to stimulate gastrointestinal motility and kill fungus. You may have heard of boswellia, or some derivative of the word, for arthritis, or as a component of skin cream. The genus of trees that produce frankincense is Boswellia.
Bensky, Dan and Andrew Gamble. Chinese Herbal Medicine: Materia Medica. Revised ed. Seatttle, WA: Eastland Press, 1993.