...where Lewis and Clark crossed the rugged Bitterroot Mountains into the homeland of the Nimiipuu (Nez Perce Tribe). Visit this unspoiled country of crystal-clear rivers, endless forests and soaring mountains. Welcome to North Central Idaho, where Lewis and Clark crossed the rugged Bitterroot Mountains into the homeland of the Nimiipuu (Nez Perce Tribe). Visit this unspoiled country of crystal-clear rivers, endless forests and soaring mountains.