Where does “samnen” come from?

samnen (Middle English) comes from Old English ġesamnian, from Old English samnian, from Proto-Germanic *samnōną.

Ancestry of “samnen”, step by step

Step	Language	Word	Meaning
1	Old English	ġesamnian	to collect, assemble, bring together, gather,...
2	Old English	samnian	to collect, bring together, gather; to...
3	Proto-Germanic	*samnōną	—

samnen — Etymology, Origin & Word History | Etymology Explorer