What is a plateau, a savanna, and trans-saharan?

Plateau:  an area of a highland, usually consisting of relatively flat terrain, that is raised significantly above the surrounding area, often with one or more sides with deep hills.

Savanna: A savanna or savannah is a mixed woodland-grassland ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses.

Trans-saharan: Trans-Saharan trade requires travel across the Sahara to reach sub-Saharan Africa from the North African coast, Europe, to the Levant. While existing from prehistoric times, the peak of trade extended from the 8th century until the early 17th century. The Sahara once had a very different environment.

Explanation:

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