Student of X
Paradigm Shifter
I came across this and thought it deserved a thread in the comparative religion section. 
Parallelism in Sioux and Sami Spiritual Traditions
There are two explanations for cross cultural mythological or spiritual similarities. One explanation for this phenomenon is diffusion, where one idea or image is physically brought from one culture and adopted by another as a result of mixing and contact. The problem with this theory is that it cannot account for correspondence between cultures with no contact.
[...]
Additionally, shamans accounts of experiences while in trance are astonishingly similar in Sioux and Sami culture. The spiritual realm is described as existing in three levels: the upper world of the gods, the physical level of the world and living things and the lower world where people and things go after death (known as Saivo to the Sami). Although these realms have slightly different meanings for each culture, the detail to which the imagery is in agreement suggests a common experience among shamans, which is transcendent of cultural and geographical boundaries.
Parallelism in Sioux and Sami Spiritual Traditions
There are two explanations for cross cultural mythological or spiritual similarities. One explanation for this phenomenon is diffusion, where one idea or image is physically brought from one culture and adopted by another as a result of mixing and contact. The problem with this theory is that it cannot account for correspondence between cultures with no contact.
[...]
Additionally, shamans accounts of experiences while in trance are astonishingly similar in Sioux and Sami culture. The spiritual realm is described as existing in three levels: the upper world of the gods, the physical level of the world and living things and the lower world where people and things go after death (known as Saivo to the Sami). Although these realms have slightly different meanings for each culture, the detail to which the imagery is in agreement suggests a common experience among shamans, which is transcendent of cultural and geographical boundaries.