We don't have synonyms for mitanni yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are mitani.
(n) :
(historical) Hurrian kingdom in northern Mesopotamia from circa 1500 B.C.E., at the height of its power, during the 14th century BC, encompassing what is today southeastern Turkey, northern Syria and northern Iraq.
(n) :
(historical) Hurrian kingdom in northern Mesopotamia from circa 1500 B.C.E., at the height of its power, during the 14th century BC, encompassing what is today southeastern Turkey, northern Syria and northern Iraq.