Chadarangam (Telugu: చదరంగము) is an Andhra or Telugu version of Indian chess, Chaturanga. It became very famous among kings and courtesans. Previously chariots (Ratha) were used in warfare, but in medieval times chariots were replaced by camels (Oṣṭra). So, the bishop in olden days was called Ratha / Śakaṭa and in medieval ages was called Oṣṭra.
Read more about Chadarangam: Origin of The Word, Names of Pieces, Movements, Terminology, Some Important Rules, Significance of These Pieces