Where does “sutherne” come from?

sutherne (Middle English) comes from Old English sūþerne, from Proto-Germanic sunþrōnijaz, from Proto-Indo-European sóh₂wl̥ — sun.

Ancestry of “sutherne”, step by step

Step	Language	Word	Meaning
1	Old English	sūþerne	southern, southerly, coming from the south; of...
2	Proto-Germanic	sunþrōnijaz	southern
3	Proto-Indo-European	sóh₂wl̥	sun

sutherne — Etymology, Origin & Word History | Etymology Explorer