The first that comes to mind is the Ottoman empire. World power in the 1600-1700s, but it failed to develop the institutions mentioned in this article and fell to Austria-Hungary, Italy, and Britain over the latter half of the 1800s.
Lithuania. Largest country in Europe in the 14th century. Lost large sections of its territory to Sweden and Russia in the late 1600s and 1700s.
All of the Native American nations that were swept aside by the United States. Much of that was because of disease, but a lot was also because the U.S. was better organized and could pick off individual tribes one-by-one.
Mongolia. Genghis Khan's empire, once one of the largest on earth. Great fighters, poor administrators. Eventually overshadowed by China.
Agree with you on all but the last example; I think the Mongol Empire was one of the marvels of human history, in terms of sheer size and coordination. It succeeded in uniting friendly tribes and warring tribes alike by allowing them to retain their cultural traditions and self-administrate, so long as it didn't violate Mongol law.
Unfortunately, the government that developed was mostly a dictatorship, and as usual it was relatively short-lived once some key family members died off and left an opportunity for others to squabble.
I think the other thing is that governments rot: almost every state begins cohesive and ends decadent. The Mongols went from cohesive to decadent in less than a generation; the North African groups that ibn Khaldun lived among tended to last 2-3 generations; the western Roman Empire lasted somewhere around 1400 years.
The history of the rulers of Byzantium/Constantinople/Istanbul also illustrates this cycle. The Byzantines began dynamic and powerful, then they became self-seeking and were conquered by the fiercely cohesive Ottoman Turks (omitting the history of the Latin Kingdom of Constantinople, which went through this cycle almost as quickly as the Mongols did), then the Ottoman Turks went from fiercely cohesive to fiercely self-interested (look up the Auspicious Incident) and collapsed in turn.
Now, the collapse part of the cycle is slowed down by a world peace that will last until/unless the United States disintegrates (and it's in trouble; look at the self-serving corruption of groups as unlike each other as the Pentagon and the labor unions) -- but I discussed both the merits and the problems of this situation in another post on this subject.
> maybe one of you could show at least one example of a "competent" nation conquering disfunctional ones before building your complete world view on it.
Countries with a mix of a stable economy, advanced technology, and organized military regularly conquered their neighbors that didn't have those things. Countries with the tech/military but not the stable economy (USSR, for instance) could have a brief go at it, but inevitably came down upon themselves.
What sort of examples were you looking for? Nations with the combination advanced technology relative to their neighbors and a well organized military have done a lot of conquering throughout history, and those with stable economies held onto their new possessions. There's so many examples I wouldn't know where to start. Rome and all of its possessions would be a decent place, or one of the many functional or dysfunctional Russian Empires, or the Unification of Japan under the Oda, Toyotomi, and Tokugawa daimyos, or Manifest Destiny in the United States...
Those are just a few to come to mind with the economy/tech/military edges, but there's quite literally hundreds, from little tiny islands taking over other little tiny islands in Oceania to the various international powers/empires. Maybe the question is with the word competent? You do need a healthy economy, advanced technology, and stable military, which in turn requires some sort of decent courts, checks and balances on military rule, some science and production happening, and so on. Complicated question - could probably go on more if you clarified a bit.
