Where does “these're” come from?

these're (English) comes from English ’re, from English are, from Middle English aren, from Old English earon, from Old English bēon, from Proto-Germanic bijōniz, from Proto-Germanic bijǭ, from Proto-Indo-European bʰey- — bee.

Ancestry of “these're”, step by step

these're traces back through two separate lines of ancestry.

via English ’re

StepLanguageWordMeaning
1English’reinflection of the verb "to be"
2Englisharesecond-person singular simple present of be;...
3Middle EnglisharenPlural present indicative form of been
4Old Englishearonthird-person plural simple present of wesan
5Old Englishbēonto be, become
6Proto-Germanicbijōniz
7Proto-Germanicbijǭbee
8Proto-Indo-Europeanbʰey-bee

via English these

StepLanguageWordMeaning
1Englishtheseplural of this
2Middle Englishþesthese; Alternative form of þas; Alternative form...
3Old Englishþēsthis
Every word from Proto-Indo-European bʰey-
these're — Etymology, Origin & Word History | Etymology Explorer