From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Mount Frypan (フライパン やま, Furaipan Yama; FUNimation "Fire Mountain", Viz "Fry-Pan Mountain"; Literally meaning "Fry Pan Mountain") is a huge mountain on Planet Earth.
When Son Goku tried to get into the castle to find a Dragon Ball, he failed and Gyumao got angry at him and fought him. He eventually had Turtle Hermit come over by sending Goku and Son Chichi. Turtle Hermit put out the fire with the Kamehameha, but ended up destroying both the castle and mountain.
Afterwards, Gyumao and his daughter, Chichi, rebuilt the castle and ruled the village from it. It was later seen various times in the anime, but never again in the manga.
Oolong described a common legend about Mt. Frypan in "...And Into the Fire!". He said, "Once upon a time it was 'Pleasant Mountain', and it lived up to the name. But about 10 years ago, a fire spirit fell form the heavens and transformed it into a mountain of eternal flame... So they say."
When Goku and Chichi got married and had their wedding in his castle in an anime filler during the Piccolo Jr. Saga, the fire started again and Goku and Chichi had to go on a quest to find the Basho Fan to put it out. At the conclusion, Goku fought against Annin to put the fire out and brought peace to Gyumao's Village again.