Question: How many square miles are occupied by the mountain range that Nez Perce Pass is located in?

Context paragraphs:
Battle of Bear Paw: The Battle of Bear Paw (also written as Battle of the Bears Paw or Battle of the Bears Paw Mountains) was the final engagement of the Nez Perce War.  Some of the Nez Perce were able to escape to Canada, but Chief Joseph was forced to surrender the majority of his followers to General Oliver O. Howard and Colonel Nelson A. Miles.  The battlefield today is part of the Nez Perce National Historical Park and the Nez Perce National Historic Trail.

Big Hole National Battlefield: Big Hole National Battlefield preserves a Nez Perce War battlefield located in Montana, United States.  The Nez Percé fought a delaying action against the 7th Infantry Regiment (United States) here on August 9 and 10, 1877, during their failed attempt to escape to Canada.  This action, the Battle of the Big Hole, was the largest battle fought between the Nez Percé and U.S. Government forces in the five-month conflict known as the Nez Perce War.  In 1992 the park was made a part of Nez Perce National Historical Park, which consists of 38 separate locations in five different states, following the flight of the Nez Percé tribe from the U.S. Cavalry.

Nez Perce Peak: Nez Perce Peak is located in the Teton Range, Grand Teton National Park, Wyoming, immediately southeast of Grand Teton.  The peak is in the central portions of the range, immediately east of Cloudveil Dome and is sometimes considered to be part of what is collectively known as the Cathedral Group.  Nez Perce rises to the south of Garnet Canyon and is a dramatic peak that dominates the skyline to the west of Bradley and Taggart Lakes.  When viewed from the western section of Jackson Hole, Nez Perce often obscures the view of Cloudveil Dome as well as South Teton, even though both summits are higher.

Looking Glass (Native American leader): Looking Glass ("Allalimya Takanin" 1832- 1877) was a principal Nez Perce architect of many of the military strategies employed by the Nez Perce during the Nez Perce War of 1877.  He, along with Chief Joseph, directed the 1877 retreat from eastern Oregon into Montana and onward toward the Canada–US border during the Nez Perce War.  He led the Alpowai band of the Nez Perce, which included the communities of Asotin, Alpowa, and Sapachesap along the Clearwater River in Idaho.  He inherited his name from his father, the prominent Nez Percé chief Apash Wyakaikt (“Flint Necklace”) or Ippakness Wayhayken (“Looking Glass Around Neck”) and was therefore called by the whites "Looking Glass".

Walla Walla Council (1855): The Walla Walla Council (1855) was a meeting in the Pacific Northwest between the United States and sovereign tribal nations of the Cayuse, Nez Perce, Umatilla, Walla Walla, and Yakama.  The council occurred from May 29-June 11, 1855.  The treaties signed at this council on June 9 were ratified by the U.S. Senate in 1859.  These treaties codified the constitutional relationship between the people living on the Nez Perce, Umatilla, and Yakama reservations.  This treaty was one of the earliest treaties obtained in the Pacific Northwest.  Washington's first governor Isaac I. Stevens secured this treaty, allowing larger portions of the land to be given to the two largest and most powerful tribes the Yakimas and Nez Perces.  These reservations encompassed most of their traditional hunting grounds.  The smaller tribes moved to the smaller of the three reservations.  Stevens was able to acquire forty-five thousand square miles of land.

Fort Lapwai: Fort Lapwai (1862–1884), was a federal fort in present-day Lapwai in north central Idaho, United States.  On the Nez Perce Indian Reservation in Nez Perce County, it was originally called Camp Lapwai until 1863.  East of Lewiston, it was located on the west bank of Lapwai Creek, three miles (5 km) above where it joins the Clearwater River at the state's first settlement, Lapwai Mission Station (now Spalding), built in 1836 by Henry Spalding.  It is part of the multi-site Nez Perce National Historical Park.  The word "Lapwai" means place of the butterflies, as the area had thousands in early summer in earlier years.

Battle of the Clearwater: The Battle of the Clearwater (July 11–12, 1877) was a battle between the Nez Perce under Chief Joseph and the United States army.  The army under General O. O. Howard surprised a Nez Perce village.  The Nez Perce counter-attacked and inflicted significant casualties on the soldiers, but they were forced to abandon the village.  After the battle, the Nez Perce retreated and crossed the Bitterroot Mountains via Lolo Pass with General Howard in pursuit.

Bitterroot Mountains: The Northern and Central Bitterroot Range, collectively the Bitterroot Mountains (Salish: čkʷlkʷqin ), is the largest portion of the Bitterroot Range, part of the Rocky Mountains, located in the panhandle of Idaho and westernmost Montana in the Western United States.  The mountains encompass an area of 4,862 square miles (12,593 km²).

Nez Perce Pass: Nez Perce Pass is a mountain pass in the Bitterroot Mountains on the border between the U.S. states of Idaho and Montana.  The pass is at an elevation of 6587 ft above sea level.  The Nez Perce Pass Trailhead offers access to the Selway-Bitterroot Wilderness and the Frank Church—River of No Return Wilderness.

Jurden Henry Elfers Barn and Field: The Jurden Henry Elfers Barn and Field is a historic site located on the south bank of John Day Creek, .33 mi east of U.S. Route 95 and north of Lucile, Idaho.  The barn and field were the site of a raid by members of the Nez Perce tribe in 1877.  White settlers had forced the Nez Perce to live on a reservation at Lapwai, and a group of young men from the tribe sought revenge against the settlers.  The men raided several sites along the Salmon River, including the Elfers' ranch.  During their raid on the ranch, the Nez Perce killed Jurden Henry Elfers, his nephew Henry "Harry" Burn Beckrodge, and hired worker Robert Bland, who were working at the barn and field at the time.  The men also stole several horses and a rifle from the property.  The raid was one of the main causes of the Nez Perce War, as soldiers at Fort Lapwai responded to the raids by attacking Chief Joseph's camp.  The barn and field are one of the few surviving sites connected to the events leading to the start of the war.

Supporting paragraphs: Nez Perce Pass Bitterroot Mountains
Answer: 4,862