The thread on Royal Houses makes me wonder; which family can trace itself back the longest (as in a family which exists today).
By trace itself; I mean that there is an unbroken legitimate or legitimization male line succession;the name may have changed.
Secondly, it must be verified and undiputed, I beleive that the Japanese Emperor has a line going back 1500 years; but lots of that is either legendary or female line.
So you’re really after the Y chromosome with the longest documented history, right?
Why restrict yourself to the male line?
Because traditionally (and I make no comment on the rightness or wrongness of this) in many cultures family has been traced through the male line and property etc has passed through that.
The Kongs. Dunno if its all male line desecndants though.
My grandmother’s family supposedly can trace its lineage back 1,000 years – presumably because they were landowners who stayed more or less in one place for all that time. Of course, that’s not all Y chromosome, and it can easily be disputed. But I’m willing to be there are a number of European families who can claim 600 or 700 years easily.
The mere fact that we’re all here – everybody reading this post – is evidence that all our ancestries go all the way back. Even if we can’t name anybody older than our parents or grandparents, that’s not the issue. We all came from the original stock. Who were they? Who knows? Better yet, who cares?
This is of course correct. The actual question being addressed here, which nobody has actually stated yet, is, “What is the male ancestral lineage that cn be documented for the longest period?” For example, I can trance ancestors through great[sup]n[/sup]-grandmothers’ ancestors back to around 1000 AD, but my documented male line peters out with my great-great-grandfather (c. 1790-1854). And there azppears to be common consent among genealogists that the lineage which can be documented the furthest back is the Kungs, Confucius’s ancestors (see Simplicio’s link.)
I agree. Everyone’s male lineage does go way back, but the problem is knowing where and details. Take a random White person in the US. Specify a certain number of generations ago. Was that corresponding male-line ancestor a Viking sailor, a Scottish Highlander farmer, a London blacksmith, a Roman legionnaire, a Greek merchant, a or a German barbarian raider? For me, I don’t know, as my male-line ancestry peters out around 1800 (early US, so I don’t even know what the “old country” really was (no, studying the last name doesn’t help out a lot, and it was alleged to have been changed anyway).
Indeed. All families are ancient, some just claim to have kept better records.
My oldest male ancestor was all of those things, plus a ninja and also a pirate. Can’t prove me wrong.
It does help focus the question to restrict to purely agnatic lineages. In some cases this means claims can be tested via Y-chromosome.
It is now widely agreed that a very large percentage of Western Europeans (including most Irish and most Basque) have a common agnatic ancestor who migrated from southwest Asia to Europe in the Late Neolithic (i.e. 3000 BC or so). I find this almost unbelievable, but the result seems confirmed when Y-dna analyses are examined in multiple ways. But that doesn’t answer OP’s question about documented lineages. (Similarly Genghis Khan’s Y-chromosome is found in millions of living males.)
Many of the pre-Norman noble families of Ireland share very similar Y-dna and are assumed to descend from the founder of the O’Neill dynasty of Kings who died ca 405. Some of these families preserve pedigrees, but I’d guess the authenticity of details is doubtful.
The Rurik Dynasty ruled Russia from the 9th to 16th century, and still has many alleged agnatic members living today. IIRC, Y-dna tests show two different lineages of Rurikids, one of which has Finnish Y-dna (N1) – confusing since Rurik himself was supposedly a Dane brought in to save Russians from Finnish marauders. :dubious:
Many European nobles have agnatic descent from the 10th-century Oberto Obizzo, including 6 Hanover Kings of England and, as very distant cousins of Hanover, a long line of Dukes of Modena.
Among the large long-lived families of Europe, I don’t know I could have overlooked the descendants of 7th-century Charibert which include 60+ Kings, many Dukes and Counts and hundreds of people living today.
There is no basis for this assumption, and it reflects very badly on the credibility of the scientists who promulgated the idea.
The logic goes something like this:
This headline is wrong in two ways:
They have drugs that can fix that now, you know. 
First: I apologize for writing “descent” where “agnatic descent” was intended. I thought this was clear in context, especially since OP specified interest specifically in agnatic dynasties.
Second: It seems that you agree that there was a common agnatic ancestor of the O’Neills (and affiliated septs) who lived at the time of the alleged Niall (or Niall’s grandfather since some septs claim descent from Niall’s brothers or cousins). it would seem clear that that progenitor was probably a major King. My understanding is that common ancestor dates computed for the affiliated septs often coincide with what is expected from traditional genealogies.
My understanding is that Niall is considered a historic figure, but if, instead, the historic figure was actually “Niall of the Eight Hostages” or some such, it would not affect the essential point: many Irish noble families are shown to have a common ancestor (probably an important King) located at about the alleged time of Niall.
Here are some Google hits that might help inform. The second may be interesting as it discusses an apparent cuckolding event in the O’Neill lineage.
I’m surprised that no one has mentioned that Confucius (b. 551BC) has known descendants.
Skimming are we? 
How valid is the Kong lineage considered to be? If valid it would be the longest such lineage, but it does span cross the famous book burning by Qin Shi Huang(*).
(* - No, not SDMB’s own Curtis LeMay – the other Qin Shi Huang. :smack:)
There is an ogham inscription of my family name on an obelisk which stands on the land we still inhabit and farm. It has been roughly dated to the first century BC. The obelisk itself is much older and is a fascinating example of the original sun worship carvings being turned in to Christian carvings with a cross now carved into the old circle.
There are other stone structures, including a sousterrain and some raths and homes which show the skills handed down through the generations.
But we couldn’t get you a first name from each generation that’s inhabited it since then, if that’s what you want.