Mt Blanc in the European Alps, Mt Whitney in the Sierra Nevadas, Mt Fuji in Japan, Mt Kilimnajaoro in Tanzania:
all are holy mountains, revered in ancient practice.
Just as is Mt Everest, or Qomoloangma, "Mother Mountain," a holy site to the peoples of Central Asia.
Hindu people of India see the rivers as holy places. They chant prayers as they bathe in the Brahmaputra and Ganges, the best-known holy rivers. They sip the water though it is full of dangerous bacteria. They bury the dead in the holy rivers, especially the Ganges.
Alas, I have not found evidence for the spiritual status of the Red River in the minds of the Caddo. But the Red gave them protein, transportation, bathing and ritual places. What site could be more important in their lives?