More than rhythm
Siberian and Sámi drums are described as horses or boats that carry the specialist, as maps of the cosmos painted on the skin, and as beings with their own biography and death.
The four-to-eight beat claim
A widely repeated claim holds that drumming near 4–8 beats per second drives theta activity and produces the shamanic state. Laboratory results are mixed and effect sizes modest; the claim is popular, partially supported, and often overstated.
Confiscation
Sámi drums were burned by missionaries and the survivors sit in European museum stores. Soviet officials confiscated Siberian drums. Repatriation claims are ongoing and are part of this topic, not a footnote to it.