43d9043f_Biome___Official_Terraria_Wiki__Name
[Block Requirements] At least 200 Crimson Grass, Crimsand Blocks, Crimstone Blocks, Red Ice Blocks, Crimson Vines, or Vicious Mushrooms [Location] Any [Compatible Biomes] Not Forest, Meteorite, or Hallow [Name] 
Crimson
Biome - Official Terraria Wiki