Even in India, where the caste system was most rigid, the practice has been officially banned since 1950. Essentially, a caste system is a rigid assignment of social status based on inheritance.

India's caste system is among the world's oldest forms of surviving social stratification. The BBC explains its complexities. The system which divides Hindus into rigid hierarchical groups based ...

Dallas Stribley / Getty Images A caste system segregates people into fixed social groups based on discriminatory notions of purity and contamination. People are placed into fixed social groups in ...

More than 240 million people in South Asia live a precarious existence, shunned by much of society because of their ranks as untouchables or Dalits at the bottom of a rigid caste system.