Megasthenes was an ancient Greek historian, diplomat, and ethnographer who lived in the 4th century BCE. He is best known for being the ambassador of the Hellenistic king Seleucus I Nicator to the court of the Mauryan emperor, Chandragupta Maurya, in Pataliputra.
During his time in India, he compiled his observations and experiences into a four-volume work titled 'Indica'. Although the original book is lost, extensive fragments have been preserved in the works of later Greek and Latin authors like Strabo, Diodorus, and Arrian.
'Indica' is one of the most important foreign accounts of ancient India. It provides valuable information on the geography, administration, social structure (mentioning a seven-class system), economy, customs, and culture of the Mauryan period. Despite some fantastical elements and misunderstandings of Indian culture, his work remains an indispensable source for historians studying this era.