Mandi was born at Dunham River junction in the country near Bandicoot Bar in the East Kimberleys. He was given the name Munnai (Munniim) by his father as a result of a dream about bubbling water and the light that shines on the water was called muniim-muniim (meaning light on the quiet water). Mandi's mother was Maggie and his father was Peter Wingngoi, who passed away at Yiralalam Hill. When his parents died, Mandi was raised at Ivanhoe Station by his father's sister, Gypsy. There the name Mandi was given to him by the boss at Ivanhoe Station, Bill Jones. Mandi worked predominantly as a stockman at Ivanhoe Station but travelled to Dunham River, Lissadell, Argyle, Newry and Carlton.
