How the Dickens did you go back so far? I can’t imagine reliable records being available prior to 1850.
When you are able to trace your ancestors back to Europe, the church kept vital records such as births, weddings, and deaths. Many of those records survive today.
Royal families had to keep track of their members to enforce property claims and noble entitlements.
I can trace my family back to the 800’s.
If there were people living there you'll find records. I have a copy of one of my ancestor's wills dated from 1690. He lived in what is now Chesapeake VA, was Norfolk County then and the records were in the Norfolk Court House. I didn't find them, my cousin did. The will itself is a hoot. The son got the farm and all the livestock, his mother got to live with him until she died, one daughter got a mattress and the other got a spoon. A spoon. Not a set of spoons.. A spoon.
Churches are a good resource too, especially if you go back to before your family's American progenitor emigrated here. They have baptismal records and marriage and death records going back to the late middle ages in some cases.
Church records are fairly reliable and they are kept for pretty much forever.
If your bloodline is Eurocentric and can get overseas the churches and other history oriented orgs have amazing records.
If I can determine which wife one of my GGG-grandfathers was born from in Tennessee then I may actually be relate to some famous folks that got drawn and quartered by the English monarchs.
Key is being able to get through the early 1800s/late 1700s. Easiest way to do that is to get back to the 1850 census. Which is the first that listed all members of the household AND where and when they were born. From there you can focus on very specific records in that area.
My family namesake I’ve been able to trace to Virginia (served in the NC militia during the rev war). Have his pension application - denied by DC- seems we didn’t treat vets any better then than now. Unfortunately while I know his mothers name I don’t know his father’s so I’ve been at an impasse for a few years trying to get one or two steps further back to make the leap.
Considered approaching it from the other side, but Reed has a wide range of area in lower Scotland and upper England that makes it difficult to find a focal point.
400-500 years is typical, but unusual to find that in each and every one of ones lines (the fam' here has one set going back to the late 15th century; another just stops dead circa 1800). The handful of people with ancestors from Iceland may be able to get back at least a couple of centuries more. What is basically NOT possible is any reliable information whatsoever, apart from the alleged noble pedigrees (and they crawled all over each other like a box of hamsters, so what the surviving docs say and the reality are going to be at least two different things), before the 10th century. Too bad, because I'd make the wild guess that a number of horndogs from history, like Mark Anthony, probably have millions of descendants, and most of them in common with one another.
She is diligent and has been working on this stuff for years.