Complex sentence: She was reported to be the oldest living person in the United States when she died at the supposed age of 120, and it is said she traveled to the Oregon Territory across the Oregon Trail at the age of 66.
Split into simpler sentences: She was reported to be the oldest living person in the United States when she died, supposedly at the age of 120. It is said she traveled to the Oregon Territory across the Oregon Trail at the age of 66.