Louis and Clark made their journey began in 1804, they describe quite well the carcasses off the cliff.... I believe there are other known references to such finds by other explorers as well, but I will stick to just Louis and Clarks accounts.
I will concede that the native americans did not stampede herds over cliffs from the begining of time... they lacked the techonology to do so. It was not until the horse was introduced to the americas and mastery of horsemanship by the native americans that they had the technological ability to create and guide a stampede to a cliff.
I will not dispute your claims that elders councilled against such behaviors... I have no way to know if they did or did not. The point I am trying to make is simple that the native americans were not the ideolized and romanticized peoples that political correctness has made them out to be.
Sadly factual truth is lost to romanticized political correctness, just as Pirates have been romanticized as well... they were far worse than even the most savage of Indian tribes, but today most people look at them as just likeable cads.
Horsecrap. A fair wind, dry grass, and fire will do the job.
When the grass grows back, it will bring even more animals in.
If you had ever seen a prairie fire (during and some time after), you'd know it.
The horse enabled more efficient hunting over a greater area. The Sioux were known for their use of the bow from horseback, hunting bison (Catlin documented that)--which meant less waste than a 'buffalo jump'.