Complex sentence: Unaware of the hostility felt for outsiders, O'Connor came to the mountains of eastern Kentucky while working on a documentary called "US", which had been commissioned by the United States Department of Commerce to be shown at HemisFair' 68 in San Antonio, Texas.
Split into simpler sentences: Unaware of the hostility felt for outsiders, O'Connor came to the mountains of eastern Kentucky while working on a documentary called "US". It had been commissioned by the United States Department of Commerce to be shown at HemisFair' 68 in San Antonio, Texas.