Hi, Lynn. One of my hardest challenges in studying [unofficially] Native American history is the translations of Native American names by the Europeans.

It is just recently that I have discovered that 'Sitting Bull' had a Native American name. I guess Sitting Bull was an English translation of that name.

Along with translations came the invariable misspellings and subtle variations on spellings.

Here is a website where his name is listed as 'Tatanka Iyotake'. Presumably, this is a reproduction of an official document.
http://www.primeau.org/StandingRock1885families.html#sitting_bull

On the PBS website, however, the name is spelled exactly as you suggest, Tatanka-Iyotanka.
http://www.pbs.org/weta/thewest/people/s_z/sittingbull.htm

Moreover, on the PBS site, his tribe is identified as 'Hunkpapa' wherein the Standing Rock census identifies the tribe as 'Uncpapa'.

Since there is so much to the history of Native Americans, I am doing what I invariably do in my genealogy research: adopt the variations and make note of them.

Spivey