Mystery: Leokwe camp - Mapungubwe - secret plaque

[Vanilpig]

Hi all,

I recently stayed at Leokwe camp. I am hoping you can help me with somewhat of a mystery.

Whilst sitting in hut #16, I saw a plaque up on the cliffs above the camp.
Upon closer inspection, the plaque reads: “Within the upside down world of the post marital tree lies a secret of gold”.

I have attached the photos of where I saw it.

Do you know perhaps what it relates to?