Where did King Ghidorah come from

After watching Godzilla king of the monsters 2019, we have so many more questions that just need answering. One of those questions, and it's an old one, is where does Ghidorah come from? MEGA SPOILERS for king of the monsters in this video. You were warned Beautiful art for the thumbnail by https://www.deviantart.com/irenbee/art/King-Ghidorah-783009805 MUSIC Hitchcockian -~-~~-~~~-~~-~- *CHECK OUT*: "NEW FOOTAGE of Godzilla vs Kong LEAKED from CCXP" https://www.youtube.com/watch?v=RPiFDzocp00 -~-~~-~~~-~~-~-