In 1991 a German art historian, Heribert Illig (ref 1) introduced the Phantom time hypothesis, an idea that our timeline had been elongated by inserting nearly 300 invented years during the early middle ages.
Illig had observed a number of peculiar things in the European history of the early Middle Ages. To account for these pecularities he came up with the idea that our current "year counting" had been manipulated. For a short description, see e.g. ref 2.

There has been much discussions on this idea, especially in Germany. Some people believe in this and others think that it is complete nonsense. Illig states, that dendrochronologists have assertained him that all is in order - the current chronology is right! Though Illig - and his colleague on this theory, Hans-Ulrich Niemitz - mean that dendrochronologists have humbled themselves to the traditional chronology of Europe. I.e. by stretching and sorting found sample data so that calculated mean values match the supposed chronology (i.e. to make 1600 years back to the collapse of the West Roman Empire). (ref 3.)

In 1998 these things were up to discussion on the ITRDB forum (e.g. ref 4.) and declared as complete nonsense. The current methods used were considered so strong together with available university data that such a mistake would never occur.

When I later read about these things, I thought, "Why not prove and demonstrate it? Why just state it as being nonsense? I have the tools to analyse this! How can I do it? What data is openly published?"

Data to be considered is that coming from areas where there are archeological wooden findings of Roman empire buildings, e.g. from Germany, Belgium, Holland and England.

The oldest British data within the ITRDB database goes back only to AD811 (brit3.rwl).

The only openly published long time series from Germany are that found in a book written by Ernst Hollstein published in 1980 (ref 5) and a mean value chronology published by Bernd Becker in 1981 (ref 6). The Hollstein data contains not only a mean value series but also 25 pages with drawn - usually mean value - ring width curves. To this we can add a Danish mean value curve going back to AD200 (ref 7.) and several short collections of Dutch data, those of special interest dated to the 4th century (ref 8). There are also mean value curves from Belgium going back to AD672 (ref 9.). Except for notably the Dutch collections, openly published ring width measurements are missing for older times!

There are indeed more data kept secret at the universities, e.g. at Hohenheim in Germany. Why that data is not openly published is unclear to me. I can only deprecate a practice that a university does not publish information of interest to a public. (Note 1.)

There is a heavy load of arguments against Illig's hypotesis. Though who is right?
If we want to check this ourselves, then we have to use published data.

With this as a background, I began collecting tree ring data related to the German area where Roman archeological wooden remains have been found. The question to be answered is, how does the Roman time ring width data match towards later time ring width data. I started with the book by Ernst Hollstein, see the next section!

1. The Aarhus Convention grants the public rights regarding access to information, public participation and access to justice, in governmental decision-making processes on matters concerning the local, national and transboundary environment. It focuses on interactions between the public and public authorities." (ref 10, 11)
Dendrochronology is considered as a science that is expected to produce data for environment research and supposed to be a potential base for governmental decision-making on environment questions. The Aarhus convention has been ratified by Germany. How does the Aarhus convention apply to dendrochronological data?