The Amarakosha (Devanagari: अमरकोशः, IAST: Amarakośa) is the popular name for Namalinganushasanam (Devanagari: नामलिङ्गानुशासनम्, IAST: Nāmaliṅgānuśāsanam) a thesaurus in Sanskrit written by the ancient Indian scholar Amarasimha. It is the oldest extant kosha. The author himself mentions 18 prior works, but they have all been lost. There have been more than 40 commentaries on the Amarakosha.
who wrote the text amarkosha during the gupta age
Amarasimha