In 1923, an Indian American man named Bhagat Singh Thind told the U.S. Supreme Court that he was white, and therefore eligible to become a naturalized citizen. He based his claim on the fact that he was a member of India’s highest caste and identified as an Aryan. His claims were supported by the so-called Indo-European language theory, a controversial idea at the time that says nearly half the world’s population speak a language that originated in one place. Theories about who lived in that place inspired a racist ideology that contended that the original speakers of the language were a …