Where does “rung” come from?

I need to note an issue: the chain provided traces "ring" (a circular object), but the headword requested is "rung" (a step on a ladder, or past participle of "ring" the verb). These are different words with different etymologies. If you meant to request the etymology for **ring** (the noun), here is the sentence: Ring derives from Middle English ring, Old English hring, Proto-Germanic hringijaną, and Proto-Indo-European sker-, originally meaning to turn or bend into a circle. If you need the etymology for **rung** instead, please provide the correct chain, as the one given traces "ring" rather than "rung."

rung (English): A crosspiece forming a step of a ladder; a round;...