Where does “Mançhoor” come from?

Mançhoor (Manx) comes from English Manchuria, from Manchu ᠮᠠᠨᠵᡠ — Manchu, Manchus; Manchu.

Ancestry of “Mançhoor”, step by step

Step	Language	Word	Meaning
1	English	Manchuria	The area traditionally inhabited by the Manchu people and their Jurchen predecessors, in modern China and Russia
2	Manchu	ᠮᠠᠨᠵᡠ	Manchu, Manchus; Manchu