What if different schools of thought exist for where something was in the past, could multiple hypothesized locations exist for a single object? Direct link with Wikipedia would also be useful
Very nice project, hope it becomes as useful and detailed as the present day OSM
If you’re thinking about contributing to OSM History maybe consider EU4 instead. Maybe you think these are different things. I don’t. One satisfies your curiosity (ie entertains you) a lot better than the other.
Maybe though OSM History could be a place, like Wikipedia, where people could settle “territorial disputes.” I don’t know, that shit, wherever it appears, is a pretty toxic part of any community. I’m not 100% sure how Europa deals with it - you can download whatever mod you want, after all, it’s your game. But my feeling is, most of this territorial dispute shit hardly affects the people talking about it at all, and the feelings of playing a video game and all that entails - positive feelings - are better than the negative ones you feel when you’re pursuing what you believe is justice in a Wiki talk page or a Twitter flame war.
Isn't that true of all historical data? It seemed so obvious to me that professional historians would share data that I asked several professional historians what the standard format was. Nobody had even considered it, as of ~10 years ago.
Obviously you can't structure all historical information, but you can do a lot of it: Location & time, other things present at that spot in space-time (people, events, weather, diseases, governments, etc. etc.), and sources. And then some unstructured fields, including one for analysis.
I'm sure that's misguided, as I'm not an historian, but it sure seems like much more value could be extracted from research if it was accumulated and shared, and not stuck in someone's personal storage, and that it would save a lot of duplication of effort.
How to represent such things on a map can become quite complex very fast. A placename from an old document may refer to multiple locations, but these are mutually exclusive. The probability of attribution may vary in each case. Different scholars may disagree about these probabilities. Etc, etc.
The two options are not mutually exclusive: Dr Shmoe and Dr Kroe can write fascinating books on the movement of the border between Hannover and Braunschweig that mostly agree but disagree on a couple of fundamental points; both could be represented, and perhaps compared, via different views.
For an existence proof: Wikipedia is able to have decent articles about (some) subjects where strong consensus does not exist.
You hit the nail on the head about trying to combine various different geo/temporal efforts to provide greater context of world history.
Our tagging system is like OSM's - very flexible - with all the strengths and weaknesses that offers. And, the tagging system has limitations that we're currently working through & around.
One strength is that any object (node, way, relation in OSM-speak) can have multiple sources. e.g. source:1=url1, source:2=url2, etc.
And, tagging areas as disupted=yes is pretty straightforward.
We have yet to hit any sensitive areas of debate, but I imagine that will happen in the not too distant future. OHM's system is inherently vulnerable to vandalism, but the goal is to allow conflicting perspectives to coexist, as long as they are sourced.
Wikipedia tags are supported & perhaps more importantly, Wikidata. Wikidata also supports OHM references.
It is mostly respecting local regulation on the topic. If you are in a country that does not regulate the area you see the disputed areas marked.
Of particular interest to me was the England/Scotland border, as I was visiting the area, and noticing that it doesn't always follow the path of the river Tweed.
When a river is a border, that is by nature always changing, how do countries decide which bit of land/islands are sovereign?
View a variety of historical maps on the left, with the same area "now" on the right, with the pointer synced between the two sides so that you can trace roads, building outlines, etc.
Also, don't miss the swipe view...
I would suggest that, if various portions the vectors could cite evidence, it would be an excellent basis for historic vector maps on Wikipedia. Currently, this whole area is a shambles.
Further, I recently learned some historical maps I had created with great effort for my Tang Dynasty text translation at https://en.wikisource.org/wiki/Translation:Manshu were deleted by some Wikipedia policy-thumber who reckoned including low resolution satellite backgrounds to contextual maps was grounds for erasing them. You'd think being an open source project for academic caliber translations you'd be able to use, you know, open sources under academic fair use. My tolerance for idiots is truly at an all time low.
can you explain a bit more about that? Not too familiar with the background of Chinese map.
He has been considering providing data to OHM, but obviously has not been convinced by this prospect yet, one of the reasons has been loss of control over his data, as there are academic institutions ready to snap this a put their name on it. It was already attempted.
I can imagine there are more researchers like this and the results of their work, all the data, is fragmented somewhere out there... and possibly lost.
These are mainly links to georeferenced raster images and databases, not vectors / OSM data. But, still -- I've already spent hours browsing old maps of my home city. For anyone interested in contributing to this project, oldmapsonline might be a great reference.
Ireland’s Ordnance Survey also has some good historical resources:
Fascinating stuff. There were some attempts with e.g. Yahoo's Geoplanet to take historical context into account. I know some people who are still working on that data set (which Yahoo released under a creative commons license): https://spelunker.whosonfirst.org/concordances/woe/
I live near a building in Berlin that has a sign "this building used to be in a different country". Also, I live on the only street still intersected by the wall. It's Bergstrasse which is intersected by the wall memorial. I remember listening to the news announcements in the Netherlands when the wall fell when I was a teenager.
Another interesting thing is that borders are kind of imprecise. We've only had GPS for a few decades and most maps predate the existence of that. Land surveillance to modern standards pretty much developed only in the last 200 years (e.g. Ordnance Survey in the UK is one of the older examples of an institute specializing in that). Post colonial dividing up of territory in e.g. Africa was done with rulers without too much regard for history, culture, or ethnical divisions. The border between the US and Canada is similar in some places. Also internal borders for some federal states are funny like that.
Besides, stuff moves around on this planet by centimeters per year in some areas. The meridian does not actually run through the little monument they have in Greenwhich for that (by over 100m). It hasn't for a long time. Rivers, which are commonly used for borders, move as well. There are some minor border disputes all over Europe (and a few major ones) as well as occasional pragmatic agreements between e.g. Belgium and the Netherlands on how to administer certain regions. Baarle Nassau of cause being the most surreal example where we are talking exclaves, enclaves and enclaves containing enclaves, etc. Some houses cross borders and have entrances/exits in different countries. It's completely nuts.
We're also big fans of WhosOnFirst!
My focus was actually much more on trying to use partly public data, and partly contributed data in order to 'render' information on top of such a map. My vision was basically to have all historically known people and there locations being visible on the map. Wikidata already has a nice start to this, but you would need a contributor model to flesh this idea out quite a bit more.
Another step after that would be the movement of armies. This could be really interesting if you could see armies moving around at different times and getting closer to each other, or pass each other by.
City population is another interesting thing. There is no easy way today to get a good estimate of what some city X population might have been at any particular period. That information is buried in all all over the place.
There are many more ideas, but having his historical map is actually awesome for me, because that was the part that I know least about. So it should be an amazing piece of the puzzle.
I will defiantly try to contribute to effort.
However so much potential for abuse and misuses .. just think of all the border disputes currently countries are having and multiply those by all the years
Glad to see it reinvigorated especially in the age of misinformation and white-washed historical data.
If the UI/UX, social-graph, and collab features evolve to a much more polished level, this could really attract a new generation of younger researchers who would really be able to scale it up.
Here is a sample UI/UX  of what a well designed timeline could potentially look like.
I remember borrowing Kinder & Hermann books when I was in high school. They were awesome (you can see them in the Internet Archive https://archive.org/search.php?query=creator%3A%22Kinder%2C+... ).
Worth taking a look at it _in_paper_ ;-)
We could add dates when pubs opened. Then when they shut we can add their closing dates; adding to the historical record and they could then be removed from the OSM map.
- I couldn't find any mention of Prussia 
- during years 1920-1938 the borders between Czechoslovakia and Poland are messing so it looks like it is a single country
I am sure anyone can find what is missing/wrong with the history of their country. This is a community project after all so I am not surprised but based on Wayback machine this project started at least 7 years ago.
Separately, missing data is different from inaccurate data, no? I'm sure we have many inaccuracies, as well, but we're working to fix those.
Of course there are plenty of borders in history that are always going to be debated. Those are academic disputes though.
IMO the main reason is that Switzerland has no natural resources so for this reason it was not invaded. You go to Africa and see the same thing, the less resources a country has, the wealthier it is.
Then you have Jews and protestant ethics in half the country that value work a lot. They welcome and support you if you are a good worker.
Then you have cold Winters that develop indoor activities like reading or workshops. They used to sleep half of the year.
But the most important thing of all, they don't have socialist or communist in power. It is a great thing that I can not vote, because the majority of workers that go there to work are leftist and will destroy the country in a few years if they could vote.
Imagine that you take the better workers, teachers, and entrepreneurs in a country and exterminate them. That is what happened in Russia and China with the communist revolutions. The most lazy and envious, aggressive and worst workers became the bosses.
That made people in those countries to literarily starve to death from incompetence and population to go down(Russia population was bigger than US of A at the start of the century). But most important, it was an inverse natural selection. The brightest and resourceful people disappeared from the genetic pool. And the culture destroyed excellence and hard work as a merit.
In Switzerland, merit culture not only survives but prospers, because without natural resources, they don't have alternatives.
Can we talk about why the oceans are that sickly, Windows 95, color of green? It’s kind of offputting..
But joke aside. I think this is awesome. Does anyone know how accurate the borders are in the German area when changing years?
I wonder how difficult it would be to build some kind of `OpenHistoricalStreetView`. We certainly have enough historical photos to do something interesting.
• although (IIRC according to something I've read recently) land surveying was practised in established "countries" since at least babylonian times, I believe there's quite a few challenges to the notion of "firm and precise borders"; going kinda back in time, this can include:
- access to precise survey data might not be easy even in modern day, with this getting harder and harder + lines more and more blurry the further we go into the past;
- as noted by others, some borders and territory ownership is heavily disputed even in the modern day;
- during wars, this gets even more unclear kinda by definition (a lot of "we control this territory" can change as frequently as many times a day, and is anyway often vaguely somewhere on a spectrum between "fact" and "wishful thinking"); [as a side note, I was kinda thinking it would be even more awesomesauce to show army movements and other population data on such a historical map as well, however this adds a whole new universe of complexity];
- a notable subcase of the above points being "deep state" situations, where the official country's officials might have a varying (sometimes tiny or none at all) authority over some parts of their territory, controlled e.g. by organised crime;
- in less "organised" countries (incl. more "primitive/aboriginal" ones), I suspect land survey might sometimes not exist at all; and/or, it may be based on some rather different cultural notions of "ownership" and "borders";
- in fact, AFAIU, the notion of "countries" is kinda something that is not a given at all historically; I believe throughout history something resembling a feudal model (or a kingdom) is much more prevalent, i.e. "I [a king] claim to be owner of this land", where I would imagine it's much too easy to make such claims; and then, with all what I wrote above, even looking at "de facto" ownership and fairly "organised" kingdoms, based on just some pop-historical literature I believe especially the closer you got to a "border" between the kingdoms, the more it resembled permanent "war territory", with "quick border raids" etc. and local skirmishes being so obvious, that nobody could even imagine it might look different in the 20th+ century (with things like The Chinese Wall and Hadrian's Wall being kinda monuments to that reality); for another possibly nonobvious organisation model from modern point of view, see ancient Greek city-states;
• time tracking being very different (e.g. "king X's Nth year of rule") and sometimes tricky to map to a universal timeline, such as the "AD/BC" (a.k.a. "CE/BCE") scheme (e.g. can we pinpoint the start of "king X"'s rule based on available sources? was it even a real king or is it purely a mythical figure? do all the sources claim the same X and N?);
• as others wrote, natural land borders & shapes definitely moved & changed over time; this can include but is not limited to:
- rivers (see other comments); artificial islands; volcano islands; volcano "mountains"; dams; floods (incl. permanent floods into land-locked depressions); drying lakes/seas (see e.g. Dead Sea, Caspian Sea);
- ice, incl. the "ice ages"; maybe a stretch case, but IIRC the Baltic Sea is known to have frozen in historical times, to the extent that inn(s) for travelers crossing it over the ice were built on that surface [though "citation needed", i.e. I totally did not fact-check it];
- go far enough in time, and continental drift itself becomes clearly apparent; this means not just broken landmass continuity or new landmass connections, but also new mountains (which often tend to become natural borders).
And that's just off the top of my head ;D I think stuff like this makes such a project super interesting and novel! :)