America's tech giants are taking a modern-day crash course in India's ancient caste system, with Apple emerging as an early leader in policies to rid Silicon Valley of a rigid hierarchy that's segregated Indians for generations.

Apple, the world's biggest listed company, updated its general employee conduct policy about two years ago to explicitly prohibit discrimination on the basis of caste, which it added alongside existing categories such as race, religion, gender, age and ancestry.

The inclusion of the new category, which hasn't been previously reported, goes beyond U.S. discrimination laws, which do not explicitly ban casteism.