Arawn is the Welsh god of the underworld. Arwan had Amaethon steal a dog, lapwing and a roebuck for him, this lead to the battle of Cath Goddeau (Battle of the trees) . In the battle Amaethaons brother Gwydion defeated Arwan. Arwan traded places with Pwyll for the span of a year and a day. In this period Pwyll defeated Arwans rival in the underworld Hafgan. Arwan and Pwyll became close friends when they exchanged back.