Customs in Mauritania
When you come in the house, first, it's very disrespectful to go with your shoes into the rooms, or into the mats or anything where they can pray. Because they say that shoes are not clean, never clean, you never know what they pick up. First of all when you get, when you come to the house, you see all the people [leave] their shoes outside. That's the very respectful manner to come into someone's house.
In this video, a Mauritanian national discusses the custom of removing shoes at the door in Northern Africa.