Complex sentence: According to legend, but not supported by the historical record, some Peraltas mined in the Superstition Mountains and that is part of the inspiration for stories about the Lost Dutchman's Gold Mine.
Split into simpler sentences: According to legend, but not supported by historical records, some Peraltas mined in the Superstition Mountains. Stories about the Peralta family mining in the Superstition Mountain are part of the legend about the Lost Dutchman's Gold Mine.