Create a portrait collage featuring four influential historical figures, focusing on different cultural leaders. Arrange the characters in a similar layout: two on the top and two on the bottom. Use a monochromatic color scheme, such as shades of blue or sepia, and ensure each figure has a distinct pose that reflects their significance. Instead of recognizable names, use generic placeholders like "Leader A," "Leader B," "Leader C," and "Leader D" with subtle background patterns representing their cultural heritage. Ensure the overall design evokes a sense of unity and respect.