It concerns the Marwari horse in Southern India. The Marwari horse is the Indian equivalent to the Arabian. They were bred to live in a desert habitat, traveling for hours and hours through sand dunes. According to the commentator of the documentary, they have very hard hoofs. I also noticed that they have very upright hooves.
This picture gives an impression of the habitat. It is just like my sand dune, at least how it is in the summer!
These horses walk hours and hours through the deep sand and go on races with hooves like this. I have to wonder if that toe dish may actually give them some grip in the sand. It certainly does not seem to be causing them any problems. A hoof formed by traveling for many miles on the sand dune. Amazing.