Where does “mnohý” come from?

mnohý (Old Czech) comes from Proto-Slavic mъnogъ, from Proto-Balto-Slavic managas, from Proto-Indo-European monogʰos, from Proto-Indo-European mengʰ-.

Ancestry of “mnohý”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	mъnogъ	many
2	Proto-Balto-Slavic	managas	many
3	Proto-Indo-European	monogʰos	—
4	Proto-Indo-European	mengʰ-	—

Every word from Proto-Indo-European mengʰ- →

mnohý — Etymology, Origin & Word History | Etymology Explorer