The most fitting answer to the question of how spatial interaction was disrupted in this place, historically, is:
A legal practice of racial segregation was in place for much of the twentieth century, restricting blacks to residence in the shaded areas.
This statement highlights a significant historical factor that affected spatial interaction, particularly in countries like South Africa, where apartheid policies would have restricted the movement and access of black populations to certain areas, thus disrupting social, economic, and geographical interconnectivity.