Āma (Ama) is the son of Ghṛtapṛṣṭha (Ghritaprishtha). Ghṛtapṛṣṭha divided Krauñcadvīpa (Kraunchadwipa) into seven varṣas, and named them after his sons. Āmavarṣa (Amavarsha) is one of these varṣas (varsha; a vast plot of land).

Devībhāgavatpurāṇa(8.13.7-8)