I am not aware of any specific example of a monkey being used as an example of cultural diffusion along the Silk Road. The Silk Road was a network of trade routes that connected China to the Mediterranean and served as a conduit for the exchange of goods, ideas, and culture between Asia, Europe, and Africa. Cultural diffusion along the Silk Road would refer to the spread of ideas, customs, and technologies from one culture to another through the trade and movement of people along the routes. Examples of this would include the spread of Buddhism from India to China, the exchange of goods such as silk, spices, and glass, and the spread of technologies such as papermaking and gunpowder.