Complex sentence: Harkins' 1832 "Farewell Letter to the American People" denouncing the removal of the Choctaws was widely published, and is still widely regarded as one of the most important documents of Native American history.
Split into simpler sentences: Harkins' 1832 "Farewell Letter to the American People" denouncing the removal of the Choctaws was widely published. To this day it is widely regarded as one of the most important documents of Native American history.