**Background**

I want to burn down a city completely. Nothing must remain, ashes to ashes, dust to dust. Even though I'm a supernatural being, I want this to happen in a natural way. I also want the destruction to not leave any traces that can be used by humanity 4,000 years later to identify what exactly happened. The event may however leave traces that make them guess what happened, but it should definitely not lead to the exact cause.

[![Fire!][1]][1]

**Details**

* Burn down a city completely, preferably within 24 hours.
* The city is built mainly with rock and clay.
* The city is situated above sea level in a semi-arid climate.

* The event may not leave any clues, that humanity 4,000 years later, can use to identify ***exactly*** what happened. Clues that make them wonder are fine however.
* Time of the event: 2,000 B.C. (approximately).

**What are my options? Any natural disaster that can be of use? Is this even possible in a natural way? Please be creative.**

I was thinking about *"fire from above"*, but a meteorite impact would be visible for more than 4,000 years.

**Edit: I removed the following requirement, to make more answers  possible:**

* The area is not volcanic active or seismographic active.

  [1]: https://i.sstatic.net/W3gc6.jpg