http://schottremovals.co.uk/cms/vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php 
In the timeline given by Egyptology, the Bent Pyramid of Dashur is older that the Black Pyramid: The Bent Pyramid is supposed to have been built around 2600BC, under the Old Kingdom by Pharaoh Snefru. The Black Pyramid is dating back from the Middle Kingdom (2055-1650BC) under Amenemhat III reign.
Even if the order of construction is correct, the timeline given doesn’t make any sense.
The Bent Pyramid, much like the Giza ones, is a thing of beauty. Perfection of architectural know-how, and the most outstanding casing of all Egypt. And Egyptology is telling us that 600-1000 years later, the “same people” built another pyramid using mud bricks. Another pyramid that is today totally falling apart due to its poor materials and construction. Technology/knowledge doesn’t disappear within the same culture. They either stay still or improve.
Which brings the real untold story.
An Ancient civilization built the Bent Pyramid using technology we still don’t understand today. The civilization disappeared taking with them all this knowledge (same goes for all other incredible sites of Ancient Egypt) and a later civilization discovered the Bent Pyramid. They tried to duplicate the work using their available methods and materials. And we see what is left today…