As it is a fact that any nation will try to enforce it's ideology through various means it have.Take the example of US.It uses diplomacy,wars,media campaigns etc to enforce it's version of democracy all over world.Now in the same context Wahhabism/Salafism is being enforce by Gulf Arab...
The reply by FunctionalAtheist is a good explanation of what is being talked about in the quranic verse.Climbing uphill etc used to be a practice in arab as there were hilly terrains to be encountered during journeys and this specific phenomena was well understood that time.