Complex sentence: However, the people of Seanchan do not all possess an Asian physical appearance, since some have been mentioned as having blonde hair, and others with African features; due to its size, Seanchan is home to a wide range of ethnicities.
Split into simpler sentences: However, the people of Seanchan do not, at the very least, possess an Asian physical appearance, given that some have been mentioned as having blonde hair. Due to its size, Seanchan can be assumed to be home to a wide range of ethnicities.