Sahara desert

Due to the change in the angle of the Earth's axis, the Sahara transforms into a savanna with lush grasses every 20,000 years.

An excerpt from the article 22 facts about Sahara desert

The current desert phase will last for the next 15,000 years, after which there will probably be another 20,000 year period when the savannah will return to these areas.

Changes in the angle of the Earth's axis affect the position of the North African monsoon, which is capable of reviving the Saharan region.