And don't forget this all happened (according to the WTS in 2370 BC). And did I mention that according to the WTS the incident at the Tower of Babel occurred some time after that? So that would leave what, 180 years (if you are generous and divide in half) for all of ancient history to have occurred before Abraham arrived in Egypt. So to summarize: the WTS is suggesting that 'evidently' all Sumerian and Egyptian history was compressed into 180 years (because before the Tower of Babel all the earth continued to be of one language - so there could not be Sumerians or Egyptians prior to that).
Notice how the WTS dances around when the great pyramids were built.