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tpo6 set6

So, it's only logical to hypothesize that a lot of these people migrated to the Nile valley when they realized that this was more than a temporary drought.

 

tpo9 set5

There were actually two periods of rain and lake formation: the first one began about 37，000 years ago, and the second one dates from about 10，000 years ago.

Keep in mind, though, that this study only looked at 19 formations … and about a thousand have been documented, so there’s a lot more work to be done.