I read that Swahili society considers several levels of knowing someone.
I know that person and he knows me
I know who that person is but we don't know each other
I don't know that person but I know people who do know him
I don't know that person and no one I know knows him but there are people alive now who do know him
I don't know that person and there is no one alive now anywhere who does know him
These can be condensed
I know him
Others know him
Nobody alive now knows him
I find this conception helpful with historical figures. Take Dwight Eisenhower. He was born in 1890 and died in 1969. My life and that of many others alive now overlaps his in time. I never met D.D. Eisenhower but I could have. There are people alive now who did know him personally. But in a few more decades, all those who knew him will be dead. At that point, we have only documents, records and such to know things about him.
Our historians and scientists probably need to offer schools and the general public revised, updated and improved terms, definitions and tools for conceptualizing periods and people of the past. The long-running tv show Bones gives an idea of what can be done today in examining records, articles, literal bones and artifacts from the past, whether it was yesterday or 35,000 years ago. As we know more about the past and about how to investigate the past, we get to look farther back in time. We get to know in finer detail and in more directions and subjects.