Where does “hierin” come from?

hierin (Finnish) comes from Finnish -in, from Proto-Finno-Ugric *-in, from Proto-Uralic -ma.

Ancestry of “hierin”, step by step

StepLanguageWordMeaning
1Finnish-inSuffix variant for the illative singular, see...
2Proto-Finno-Ugric*-in—
3Proto-Uralic-ma—
Every word from Proto-Uralic -ma →Every word from Finnish -in →Every word from Proto-Finno-Ugric *-in →