User blog comment:Kogath/Monster Hunter: World Discussion/@comment-25083735-20190720031910/@comment-31029678-20190720064933

Biomes are large, it's not just those parts we can visit and explore... probably Acidic Glavenus lived in other parts f the Rotten Vale and now (maybe due to Velkhana's action) it started roaming in Odogaron's territory.