Where does “پچھم” come from?

پچھم (Middle Hindi) comes from Sanskrit पश्चिम, from Sanskrit पश्चा, from Proto-Indo-Iranian pasčaH, from Proto-Indo-European *pos-kʷéh₁.

Ancestry of “پچھم”, step by step

StepLanguageWordMeaning
1Sanskritपश्चिमwest, western
2Sanskritपश्चाbehind; after, later; westward
3Proto-Indo-IranianpasčaH—
4Proto-Indo-European*pos-kʷéh₁—
Every word from Proto-Indo-European *pos-kʷéh₁ →Every word from Proto-Indo-Iranian pasčaH →Every word from Sanskrit पश्चा →