Around the middle of the first millennium CE, the Sanskrit scholar Amarasimha composed the Amarakosha, the most renowned lexicographical work in the Sanskrit tradition, likely in India. This thesaurus is organized thematically and groups words by subject, providing synonyms and grammatical information. It became the standard reference for Sanskrit poets and scholars, and its influence extended across South and Southeast Asia.

The Amarakosha was an indispensable tool for Sanskrit poets, providing them with a rich vocabulary of synonyms and enabling the composition of ornate and allusive verse. Its thematic organization influenced the structure of later Indian lexicography and poetics, and its authority ensured that Sanskrit poetic conventions were transmitted across generations. The work remains a cornerstone of traditional Sanskrit education and literary culture.