Mantri is a word of Sanskrit origin, used in Asian cultures with a Hindu tradition (even those that later adopted Buddhism or Islam). It is used for a variety of public offices, from fairly humble to ministerial in rank. The term also forms part of a number of compounds. It is the root of the westernised word Mandarin, for a bureaucrat of the Chinese empire.
These are just a few examples of the use of this root in various political systems
in Satara, where the Peshwa (formally First Minister) took over political power from the nominal Monarch : Mantri was used as synonymous Sanskrit version of Waqnis (Fourth Minister)
It is used synonymously with Minister in many Indian languages
in Deli the title of Tengku Perdana Mantri was created 1st February 1923 for Y.A.M. Tengku Harun al-Rashid ibni al-Marhum Sultan Ma'amun al-Rashid Perkasa 'Alam Shah, eldest brother of the Crown Prince (Sultan the next year) and Wakil of Bedagai 1932
in Kutai, Perdana-mantri was the first great Officer of state, or Chief Minister
in Sambas, Radin Mantri was a highl stles for princes of the blood, e.g. borne by H.H. Sri Paduka al-Sultan Tuanku 'Abu Bakar Taj ud-din I [al-Marhum Janggut] ibni al-Marhum Sultan 'Umar Akam ud-din, future Sultan of Sambas, before his accession on the death of his father, 1790
in Yogyakarta and Surakarta palaces - the term is part of administrative titles for positions within the palaces and places that they control.
Cambodia
In Cambodia, the Sanskrit title was often corrupted; e.g. Udarma Mantri to Udom Montrey