According to the two maps, B. the Rocky Mountains define the western boundary of the Plains Native American cultural zone.
What are the rocky mountains?
Massive mountain ranges known as the Rocky Mountains run from Canada to central New Mexico. Around 170 to 40 million years ago, during a time of active plate tectonics, they began to take shape. The western United States was formed by three significant mountain-building periods. Western North America is home to the Rocky Mountains, which extend over 3,000 miles (4,800 kilometers) from northernmost British Columbia to Idaho, Montana, Wyoming, Colorado, and down to New Mexico in the United States. The Rocky Mountains include the Canadian Rockies. those Rocky Mountain states, such as Colorado, Idaho, Montana, Nevada, Utah, and Wyoming, as well as occasionally Arizona and New Mexico.
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