You might be interested in threads from the FAQ section on “Examples of Asians and Africans in Pre-Modern Europe":
Did black people have rights in England before the slave trade began? - 54 comments, over 2 years old.
This thread discusses the treatment of several Black British people before slavery became an important economic driver for the British and also has a lively discussion of the definition and details of slavery compared to other forms of labor.
How alien would the idea of a non-white person be to somebody living in medieval England? - 8 comments, over 1 year old.
More examples and several users provide information on beliefs and attitudes that white Europeans towards nonwhite people.
How could exotic Easterners come to be in a Medieval English Court? - 6 comments, over 8 months old.
Multiple Late Medieval and Renaissance examples, articles, and book sources all packed into just a few comments.
Were there any Black (African) knights in Medieval Europe? - 28 comments, over 1 year old.
Although not all of them knights, several examples are brought up and discussions are had about the sources involved.
Were there any Sub-Saharan Africans living in Medieval Europe? - 14 comments, over 8 months old.
A commenter gives examples in Southern and Eastern Europe.