Read my word a day say:
[From Portuguese mandarim, from Malay menteri, from Sanskrit mantri
(counselor), from mantra (word or formula), from manyate (he thinks).]
I use to see a theory that Mandarin comes from the word Manchurian…
but today Mancurian is a slang for people from Manchester.
The Portuguese were in contact with China very early. I do believe that the word mandarin comes from the Portuguese mandarim, meaning an official, which is a translation of the Chinese word guan. The language Mandarin, which is now called guoyu or putonghua, used to be called guanhua - the language of officials. It certainly does not come from the words Man daren meaning a Manchurian gentleman. Note: mandarin also has the meaning of an official in English.