In studying Korean shamanism, you don’t get very far before you run into a problem of terminology. What exactly is shamanism? If you define it as a spiritual or religious practice in which a practitioner goes into a trance and communicates with spirits, that’s all well and good, but it’s not particularly Korean. Shamans do that sort of thing the world over. In some contexts it might be useful to connect the spiritual practices of Koreans, Native Americans, sub-Saharan Africans, Pacific islanders, but at this point you’re using a pretty broad brush. It would be like lumping all the Jews, Christians, Buddhists, Muslims, Zoroastrians and Manichaeans together under a unifying term for religious practices that focus on prophets, revelations, texts and salvation (soterialism?).
The simplest solution is to go narrow. Instead of shamanism, we can say that we’re studying Mugyo (무교), the Korean term for the traditional practices that typically get lumped into Korean shamanism. A common English term is Muism, which lacks poetry but more or less works.
Except that now we’ve drawn too small a circle. Muism, as it happens, looks a lot like the indigenous (or at least non-Buddhist, non-Catholic, non-Confucian, non-Communist, non-anything else) religious practices of Vietnam, China, Taiwan, and probably a few other places in the neighborhood (Shinto comes to mind, though that’s a vexed topic). East Asian shamanism? Maybe. But then the focus on the practitioner and the practice, the trance and the channeling, overlooks a larger universe of religious confluences and similarities.
For now, I suppose I’ll make due with “Asian shamanism” for the more general, Muism for the strictly Korean. But I wish there were a better term out there for the interwoven traditions of the region.