Maybe, I've read in a couple different places that the term 'black Irish' was used prior to that time. I've even read one guy who thinks that the term relates to a tribe of 'Bushmen' who were in Ireland in prehistory. The same guy speculates that these same folks were the source of the myth of Leprechauns...and, the Bushmen do have some traits and habits that are similar to the myths of the Leprechauns. Who knows?
August 24, 1804 John Ordway Back about 2 miles we are informed that their is a verry high hill called Hills of the little Devils by the natives & they amagan that it is inhabited by little people with Big heads & they are afraid to go up to them for fear they will shoot them with their Bows & arrows,
August 25, 1804 William Clark
In a northerley derection from the Mouth of this Creek in an emence Plain a high Hill is Situated, and appears of a Conic form, and by the different nations of Indians in this quarter is Suppose to be the residence of Deavels. that they are in human form with remarkable large heads, and about 18 Inches high, that they are very watchfull and are arm'd with Sharp arrows with which they Can Kill at a great distance; they are Said to kill all persons who are So hardy as to attempt to approach the hill; ... So Much do the Maha, Soues, Ottoes and other neighbouring nations believe this fable, that no Consideration is Suffecient to induce them to approach the hill.
William Clark
Capt. Lewis & Myself concluded to go and See the Mound which was Viewed with Such turror by all the different Nations in this quarter, ... our Dog was so Heeted and fatigued we was obliged [to] Send him back to the Creek, ... Capt. Lewis much fatigued ...
One evidence which the Inds give for believeing this place to be the residence of some unusial Sperits is that they frequently discover a large assemblage of Birds about this Mound [this] is in my opinion a Sufficent proof to produce in the Savage Mind a Confident belief of all the properties which they ascribe [to] it.