Rocks in wadi.

This sort of choke point is quite common in most of the major wadis in Oman. Finding a way around or over can be a challenge, especially in the summer months when the rock is warm (hot) and covered in fine dust.
Accumulation of rock like this one is the result of the many Cyclones Oman has endured over the centuries; well trodden paths and even Falaj get blocked. There are several instances were a whole village has moved because of the loss of water when a Falaj gets blocked or damaged beyond repair.