Although , the name khan is prevalent almost worldwide, the true khan family are the descendents fo the Icursian tribe of ancient Egypt. Micheal Hart, one of the most famous eugenicists traced the Khans to be the true proto-hamitic or the Aryan peoples. Although the Khan families are predominantly caucasian throughout the Middle east and Europe, they also include a vast number of muslim families in places like India, China and south east asia. An interesting fact: Khan families in Europe and elsewhere have for long provided excellent athletes, musicians and actors in various countries.
for eg. Oliver khan, Justino "khan" fontaine, Omar khan(later known as Omar Sherif in the U.S), Aechillius Mehmet Khan (known as Tarkan in the Arab world), Muhammed Khan (famous French actor in the 90's).