Dashavatara refers to the ten principal Avatars. In Vaishnava philosophy, an Avatar most commonly refers to the 'descent' and dasa refers to 'ten' in number. The ten most famous incarnations of Vishnu or sometimes Krishna are collectively known as the Dashavatara. This list is included in the Garuda Purana (1.86.10-11) and denotes those avatars most prominent in terms of their influence on human society.
Parashurama, Rama with the axe, appeared in the Treta Yuga. Parashurama a Brahmin, the sixth avatar of Vishnu, belongs to the Treta yuga, and is the son of Jamadagni and Renuka. Parashu means axe, hence his name literally means Rama-of-the-axe. He received an axe after undertaking a terrible penance to please Shiva, from whom he learned the methods of warfare and other skills.