I found interesting that the theme about Cambodia came to the talk since I see many similarities between Maya and Khmer as the best examples of "Cities in the Jungle" cultures. I suppose is because the similar enviromental challenges.
Didn't both of them rise and collapse in very similar ways? I mean Khmer Empire and Classical - Yucatan - Maya
1) A tropical jungle region with an extreme climate and humidity is not really that conductive to early civilization, therefore no "cradle of civilization" participation here very early on
2) Climate changes across centuries and makes certain small area actually very conductive to agriculture and high/very high population density
3) Great civilizations appear, very high urbanization, population density, monumental architecture etc
4) Humans don't know anything about climate and ecological balance in those eras, so they just exploit everything as much as they can, up to the limit
5) Climate changes for the worse and because everything relied on very delicate balance, and humans didn't grasp that and used land to the max, everything collapses rapidly
6) Civilization in the entire area (Yucatan, Angkor) collapses, writing included, jungle grows over cities, less magnificent descendants of magnificent civilization continue in different areas; centuries later population density in those areas is still either mediocre (Angkor) or very low (Yucatan) in comparision with neighboring lands
It also reminds me of the way Pueblo and Missisipi civilization areas suddenly rose and utterly collapsed over span of several centuries, although here the problem was with too arid climate instead, and they have never achieved nearly the same sophistication as Maya and Khmer.
I don't know any more examples other than these four, although maybe I vaguely recall something less dramatic about civilization centre of gravity in Java moving from central to eastern across centuries.