20,000 - 12,000 years ago According to the most popular theory, Asian nomads cross the Bering Strait to arrive in North America.
1830s Westward-moving European settlers begin to kill bison.
1872 Yellowstone National Park is created.
1874 Gold is discovered in the Black Hills of South Dakota, bringing a new wave of white settlers to the Lakota homelands.
June 25, 1876 Lakota defeat U.S. troops under the command of George Armstrong Custer at the Battle of Little of Bighorn in Montana.
1890 The last Lakota holdouts are subjugated by Army troops; Native Americans are forced to live on reservations.
1902 Twenty-three bison are discovered alive in Yellowstone National Park.
1910 Brucellosis disease is first found in domestic cattle in Illinois.
1917 Brucellosis is first found in Yellowstone bison.
1934 The U.S. Department of Agriculture embarks on its campaign to eliminate brucellosis from the United States.
Winter 1984-85 State and federal representatives eliminate 88 bison outside the borders of Yellowstone National Park.
1985 The state of Montana is deemed brucellosis-free.
1985-1996 State and federal officials and licensed hunters kill 1,899 bison outside of Yellowstone in a state-sanctioned hunt.
1995 Montana Department of Livestock requested to serve as lead agency for Montana for bison/brucellosis disease management.
Winter of 1996-97 More than one third (1,049) of the Yellowstone herd of bison are killed.
Spring 1997 Buffalo Nations is formed (later known as the Buffalo Field Campaign) and starts actions, which include protests, civil disobedience, blocking state and federal officials and disseminating information.
December 20, 2000 The Interagency Bison Management Plan is drafted and agreed upon by Montana Department of Livestock, Montana Department of Fish, Wildlife and Parks, National Park Service, U.S. Forest Service and the U.S.D.A. Animal and Plant Health Inspection Service (APHIS). The Plan includes three steps for management and three zones for both the North and West boundaries. It calls for hazing bison back into Yellowstone National Park as a first priority. When hazing is no longer effective, capture and testing is mandated. Bison that test negative are released on public land; those testing positive are sent to a slaughter facility, with heads, meat and hides donated to a tribal organization or other charity. Under the final step of the Plan, untested bison will be allowed to move freely into parts of Montana.