Knowing what major events were happening or what technologies were available to your ancestors during their lifetime could be useful when researching your family's history. For example, if they lived after 1839, there may be a photograph of them out there somewhere. If they lived after 1827, they may have been associated with or migrated west on the newly built railroads. If they died in New England in 1636, they could have been killed in the Pequot War.