何なん万まん年ねん

noun, adverb

tens of thousands of years; many millennia

Used to express an extremely long time span, often in hyperbolic or figurative contexts. Can function as a noun or adverbially.

See also: 万年

• この化か石せきは何なん万まん年ねん前まえのものだ。

  This fossil is from tens of thousands of years ago.

• 何なん万まん年ねんも変かわらない景色けしきが広ひろがっている。

  A landscape that has remained unchanged for tens of thousands of years stretches out.