The first white man known to have explored this region is Sieur de la Varendry, who made his way up the Missouri River during the years 1730 to 1744, and reached the Rocky Mountains in January 1743. He did not remain, and did not contribute any valuable historical information about the country.

The journals of Lewis and Clark, recording their explorations in 1804 and 1805, are full of interesting and valuable information. With their interpreter, Charbonneau, a French Canadian, and his wife, Sacajawea, known as the bird woman, and members of the party, they reached the head of the Missouri River in July 1805 and Sacajawea proved a valuable guide to them in this part of the journey, as this was her homeland. The explorers were camped close to the spot where her countrymen, the Shoshones, or Snake Indians, had their huts five years before, when they were attacked by the Minnetare of Knife River, who killed many men, women and boys and made prisoners of the girls, some women and four boys. Sacajawea, one of the prisoners, was sold to Charbonneau, who reared her and married her. A monument has been erected in her honor in the town of Three Forks by the Daughters of the American Revolution.

Manuel Lisa with a group of men ascended the Missouri River in 1807, and established a trading post at the confluence of the Yellowstone and the Big Horn rivers. He returned to St. Louis, and with eleven others formed the Missouri Fur Company, with a capital of $40,000. In 1809, they came up the Yellowstone River, crossed what is now known as the Bozeman Pass, and established a post at the Three Forks of the Missouri that was abandoned a few years later. No permanent settlement resulted from Emanuel Lisa’s trading post, but for many years the Bozeman Pass served the fur trader, as well as the Indians as a gateway to the Northwest.

George Droulliard, John Potts and John Colter of Lisa’s group had been with the Lewis and Clark expedition. Droulliard and Potts were killed by Indians near Three Forks, and Colter had a narrow escape when chased by Indians, after being stripped of shoes and clothing, saving his life by jumping into the Madison River and hiding over night in a beaver house. Colter is believed to have been the first white man to view Yellowstone Park.