TIL that around 23,000 years ago a population of humans returned back to Africa after the initial out-of-Africa migration 40,000 prior. They are now attributed as the genetic origin of the inhabitant of the Horn of Africa and possibly early Egyptian populations. User xxhamudxx, in the Today I Learned (TIL) subreddit, 09 Aug 2015
Early Back-to-Africa Migration into the Horn of Africa : Eurasions have been migrating to the Horn of Africa for 20,000-30,000 years User wazzoz99, in the Reddit Science subreddit, 01 Apr 2015