Introduction to the archway: The terrain at the Gyatso La Mountain pass is flat. A simple archway stands across the road. It clearly says: You have entered the Everest National Nature Reserve. Gyatso La Mountain Pass is the highest pass passed by on the way from Lhasa to Kathmandu, Kingdom of Nepal on the 318 National Highway. The colorful prayer flags make a loud noise when blown by the strong wind on the mountain pass.