for - progress traps - exceptional civilizations - Egypt and China

progress traps - exceptional civilizations - Egypt and China - While 1,000 years seems to be the norm for the lifetime of an average civilization, China and Egypt have both endured 3 times as long - Egypt had the self-replenishing Nile River with topsoil being washed down from Ethiopia every year to maintain their soil fertility - So they avoided the salinity problem until modern times with the construction of high dams that have had unintended consequences - China also had unusual conditions of exceptionally deep layers of annually replenished topsoil called loess that were formed by being blown in by the wind from surrounding areas