Complex sentence: After the completion of Fort Mohave, Irataba and several hundred of his most ardent supporters moved to the Colorado River Valley, where according to Sherer they relied "upon the federal government to help make it an Indian farming sanctuary".
Split into simpler sentences: After the completion of Fort Mohave, Irataba and several hundred of his most ardent supporters moved to the Colorado River Valley. According to Sherer, they relied "upon the federal government to help make it an Indian farming sanctuary".