Former Transformers Creative Manager Rik Alvarez spoke to the attendees at TFcon 2018, to give details of an unused plot for the 4th Transformers Live Action Movie.
Some of these unused ideas for Age Of Extinction clearly explains why we saw several concept art based on a desert landscape including a nomad Lockdown. It also explains the teaser logo of Transformers 4 which was also desert themed.
According to Mr. Alvarez, the story takes place following the events of DOTM where a group of Decepticons lived in exile under the guidance of Lockdown. The group, known as ‘The lords of deception‘, hunts and kills Ratchet (taking away his signature buzzsaw) as well as Epps; allowing the latter to jump franchises to be Roadblock of G. I. Joe: Retaliation until Dwayne “The Rock” Johnson was brought into the cast of the second movie.
The story also explains the origin of the Dinobots for the live action series and features a very Samurai-esque Optimus Prime.
You can listen to the full description, below: