Where does “उससे” come from?

उससे (Hindi) comes from Hindi से, from Sanskrit समम्, from Sanskrit सम, from Proto-Indo-Iranian samHás, from Proto-Indo-European somHós, from Proto-Indo-European sem- — together, one.

Ancestry of “उससे”, step by step

उससे traces back through two separate lines of ancestry.

via Hindi से

Step	Language	Word	Meaning
1	Hindi	से	indicates association or mutual dealing;...
2	Sanskrit	समम्	—
3	Sanskrit	सम	same, equal, alike; equivalent to, like,...
4	Proto-Indo-Iranian	samHás	same, equal
5	Proto-Indo-European	somHós	same, alike
6	Proto-Indo-European	sem-	together, one

via Hindi उस

Step	Language	Word	Meaning
1	Hindi	उस	that - oblique case only, see below for direct;...
2	Proto-Indo-European	āws-	—
3	Proto-Indo-European	h₂ews-	dawn; east; to draw water, scoop up

Every word from Proto-Indo-European sem- →Every word from Proto-Indo-European somHós →Every word from Proto-Indo-Iranian samHás →