In history, people were often discriminated against because of their color.

color 的意思是"颜色"，在这里特指"肤色"。 discriminated 是动词 discriminate 的过去分词形式，表示"被歧视"。discriminate 由前缀 dis-（表示"分开"）和词根 crimin（判断）组成，原意是"区别对待"，引申为"歧视"。 because of their color 指"因为他们的肤色"，这里的 color 特指人种或肤色的差异。