who invented the sankaku jime (triangle choke)?

Some say Tsunetane Oda but I think that was only because he was one of the early ones to record it on video:
https://www.youtube.com/watch?v=_of8P71itic&feature=youtu.be&t=8m53s
https://en.wikipedia.org/wiki/Tsunetane_Oda

Depending which version you mean, it's certainly a lot older than that: http://ancientolympics.arts.kuleuven.be/picEN/slides/P0438.jpg.html

PointyShinyBurning wrote:Depending which version you mean, it's certainly a lot older than that: http://ancientolympics.arts.kuleuven.be/picEN/slides/P0438.jpg.html

I mean the types we see in grappling sports nowadays.

I don't read too well but it seems from Japanese Wikipedia that Kosen competitors named Kanemitsu (金光彌一兵衛) and Hayakawa (早川勝) started using it in 1922, naming it matsuba-garami or pine leaf entanglement (松葉がらみ):
https://ja.wikipedia.org/wiki/%E4%B8%89%E8%A7%92%E7%B5%9E%E3%82%81

That's an interesting historical picture. Maybe the legs were used for control (in order to perform the arm lock) rather than for the purpose of strangulation as in sankaku jime. How hard would it be to choke someone from the top like that? I am not familiar with that.