What is the definition of cultural barrier?

Quite often, barriers to diffusion are categorized in two ways

• Cultural
• Natural

Cultural barriers could be a unfriendly tribe who doesn't speak to other tribes, or two neighboring states who share different languages, thus, preventing or slowing the diffusion.

Natural Barriers would be the natural landscape from inhibiting the spread of cultural diffusion, such as mountains, deserts, oceans, tundras, distance, and weather.