Call me morbid.
So far:
Indochina
Afghanistan
Russian steppes
any others?
One page I saw had Belgium as the country most visited by battles in Europe – but that would have to be confirmed.
This page has some statistics that might help, while The War List has some of the more historic ones.
Israel.
Or the Transjordan region, if you will.
The place where Africa, Asia, & the path to Europe join. From the early Stone Age conflicts between Neanderthals & Early Modern Man, on to the Bronze Age wars, to Alexander The Great’s unstoppable rampage, to Rome destroying Masada, to the Crusades, to the Turkish conquest of the region, to the Colonial era, to WW1, to today’s Arab-Isreali Wars, to the Intafada.
Not to mention the Biblical record.
YIKES! ALL THAT BLOOD!
Lake Totenkopf in Ingolstadt, Bavaria
Bosda: Disagree on Israel/Transjordan. I really think it has mostly been a side theatre in history - armies march through, but there have been fewer engagements on its ( or over its ) soil. There are exceptions, but most of the real fighting has been either in Syria to the north or west into Egypt proper. Expand the region a bit and I might agree.
At any rate is the OP looking for where they bloodiest fighting has occurred or just areas which have seen the most repeated campaigning? There are lots of strategic chokepoints that have been the site of a lot of fighting. John Keegan cites Thrace ( such sites Adrianople/ Edirne, ancient Lysimacheia, etc. ), the Europe/Asia chokepoint, where, unlike the Transjordan region, a lot of battles have actually been concentrated. The fields of Panipat outside of Delhi are another.
- Tamerlane
I was looking for areas which have been repeatly invaded, with the (near) invariable result that the invading army (let’s leave out aircraft/missles) was destroyed - not just areas of repeated conflict, but areas which have proven far too costly to invade.
(The middle east has been successfully invaded/occupied many times, as has Belgium, so those don’t count - compare that to the Russian steppes, where, IIRC, NOBODY has ever “won” an invasion).
I’ll add Switzerland, though I doubt that many have tried in the last few hundred years.
coughMongolscough
I’ll think on it, but just about everybody has been brought low at one time or another, the regions of Russia and Afghanistan ( Afghanistan in particular is a very young country - it has been controlled by myriad different dynasties throughout history ) included.
- Tamerlane
Russia in the Winter. Accept no substitutes.
1798-1803 isn’t all that successful, although I’m surprised that so many countries got involved.
Saskatchewan? 
Well, what happened in 1803 wasn’t that the brave Swiss patriots threw out the evil French oppressors; rather, Napoleon dissolved the Helvetic Republic and replaced it with the Swiss Confederation, which was still something of a French satellite until the collapse of the Empire. With Napoleon’s fall in 1815, the European Great Powers guaranteed perpetual Swiss neutrality, but this seems to have been more the wishes of the European Great Powers (if it’s neutral, then at least the other guys don’t have it) than of the doughty Swiss forcing the world to leave them be. To be sure, the Swiss clearly had their act together to a much greater extent in, say, 1940, than they did in 1798; in 1798, the Swiss were disunified and disorganized, whereas at later periods they were in a better position to confront potential aggressors. (There’s also that whole “convenient Swiss banking system” thing, but that would be another thread.)
The larger point is that terrain alone won’t stop any reasonably well-organized army. Terrain can certainly be a big help to a defending force, but terrain–even the Alps–won’t stop an invading army all by itself, if there’s no defending force able and willing to defend it.
Hmm… Don’t remember anyone trying there. (Montcalm? Wolfe? I’m a little fuzzy…) It’s definitely Brass Monkey territory.
I was just about to say that, Tamerlane! And (pace Harry Lime) they did it in winter.
I believe that the Poles and Turks have also been successful at various times campaigning in Russia. Russia’s invincible reputation is largely based on the Napoleonic invasion and Barbarossa, but the staggering scale of those defeats has overshadowed the rest of history.
As for Afghanistan, during the 17th and 18th centuries it was successfully occupied by no less than three powers: Persia, the Mogul Empire, and (of all places) Uzbekistan! And it’s not as if the Red Army was destroyed when it invaded Afghanistan; it just couldn’t stamp out the mujaheddin.
Switzerland’s record is pretty damn impressive, especially during the Middle Ages, although it’s true as MEBuckner says that even the Swiss are not undefeated.
I know it dosen’t count towards the spirit of what the OP was asking (too young, not enough conflicts ), but I would like to point out that nobody has ever successfully invaded The United States.
That’s not what he means. The US doesn’t count because of the defeat of the natives.
And more on Afghanistan, it’s not like the British were unsuccessful there, either.
Are we talking total # of deaths, or total # of armies defeated?
If the latter, I still say Israel/Transjordan.
Yeah, but not without a heavy price.
Riel, although it was still NWT rather than Sask then.
Well the Jordan River runs up past Beirut, so in that sense you can add a few to the tally sheet. But if you mean Transjordan/ Israel in the modern sense, I still disagree.
Megiddo, the various squabbles and conquests of the Jewish states, Raphia, Yarmuk and a few more minor engagements of the Arab conquest, certainly Ayn Jalut, perhaps Hattin and a few engagements during the Crusades ( but there were few set-piece battles in that period ), nothing much at all during most of the Mameluke period ( other than Ayn Jalut ), essentially nothing during the even-longer Ottoman period, then to the modern Arab-Israeli wars.
Not in the running for tops in my book, but YMMV :).
- Tamerlane