American Mounds vs European Mounds

A quick look at Native American Mounds versus European Mounds is made. The question is asked as to why they are similar.

https://en.wikipedia.org/wiki/Tumulus

https://en.wikipedia.org/wiki/Mississippian_culture

http://tyranena.com/

https://en.wikipedia.org/wiki/Gamla_Uppsala

https://en.wikipedia.org/wiki/Motte-and-bailey_castle

https://en.wikipedia.org/wiki/Mound

https://en.wikipedia.org/wiki/Burgstallkogel_(Sulm_valley)

https://en.wikipedia.org/wiki/Mound_Builders