Footprints of the Frontier

Why isn't this excellent documentary series on IMDb? I've watched the 40 or so episodes on tubi and enjoyed them very much. Native Americans and women are chronicled with interest and respect. 

"From the early days of manifest destiny and wagon trails to the latter days of train robberies and armed conflict, Footprints of the Frontier is your premiere show for the Wild West portion of American history. We cover the explosive yet enlightening events that define the old United States, starting in the earliest years of America's discovery and lasting until the turn of the 20th century." [Prime's sales pitch.]