Question: The Pahute Mesa's southeast region lies in what was formerly known as what?

full_context: Document 1: Lovelock Aerial Gunnery Range: Lovelock Aerial Gunnery Range was a World War II facility in two Nevada areas used for "aerial gunnery, strafing, dive bombing [and] rocket fire". By 21 November 1944, the Lovelock Range had been approved by the Secretary of the Navy to be developed for Naval Air Station Fallon, and on 13 January 1945, "Lovelock Air to Air" began when "leased under the Second War Powers Act". By February 1945, land was being acquired for the North Range in the Black Rock Desert which was 1122 that included 64.4 of "Patented" (leased private) land. The South Range in the Granite Springs Valley was 2436 , and in March 1945 "1920 Acres more" were added.
Document 2: Santa Susana Field Laboratory: The Santa Susana Field Laboratory is a complex of industrial research and development facilities located on a 2,668 acre portion of the Southern California Simi Hills in Simi Valley, California. It was used mainly for the development and testing of liquid-propellant rocket engines for the United States space program from 1949 to 2006, nuclear reactors from 1953 to 1980 and the operation of a U.S. government-sponsored liquid metals research center from 1966 to 1998. The site is located approximately 7 mi northwest from the community of Canoga Park and approximately 30 mi northwest of Downtown Los Angeles. Sage Ranch Park is adjacent on part of the northern boundary and the community of Bell Canyon along the entire southern boundary.
Document 3: Trinity (nuclear test): Trinity was the code name of the first detonation of a nuclear weapon. It was conducted by the United States Army at 5:29 a.m. on July 16, 1945, as part of the Manhattan Project. The test was conducted in the Jornada del Muerto desert about 35 miles (56 km) southeast of Socorro, New Mexico, on what was then the USAAF Alamogordo Bombing and Gunnery Range (now part of White Sands Missile Range). The only structures originally in the vicinity were the McDonald Ranch House and its ancillary buildings, which scientists used as a laboratory for testing bomb components. A base camp was constructed, and there were 425 people present on the weekend of the test.
Document 4: Desert National Wildlife Refuge: The Desert National Wildlife Refuge is a protected wildlife refuge, administered by the U.S. Fish and Wildlife Service, located north of Las Vegas, Nevada, in northwestern Clark and southwestern Lincoln counties, with much of its land area lying within the southeastern section of the Nevada Test and Training Range. The Desert NWR, created on May 20, 1936, is the largest wildlife refuge in the lower 48 states of the United States, encompassing 1.615 e6acre of the Mojave Desert in the southern part of Nevada. This Range is part of the larger Desert National Wildlife Refuge Complex, which includes the Ash Meadows National Wildlife Refuge, the Moapa Valley National Wildlife Refuge, and the Pahranagat National Wildlife Refuge.
Document 5: Cactus Range: The Cactus Range is a small mountain range in Nye County, Nevada. The range lies southwest of Cactus Flat and north of Pahute Mesa. Goldfield lies 23 mi to the west in Esmeralda County. The range lies within the restricted area of the Tonopah Test Range.
Document 6: Mesquite Valley: Mesquite Valley is a valley in Clark County, Nevada and Inyo County and San Bernardino County, California. Mesquite is an endorheic basin with Mesquite Lake at is lowest point at an elevation of 2,536 feet / 773 meters. This valley trends northwest and southeast with a head at to the southeast near State Line Pass and another head at at the southwestern end of Pahrump Valley, at an elevation of 2,808 feet / 856 meters, between the Kingston Range and Black Butte to the northwest. It is bounded on the northeast by the Spring Mountains, by the Mesquite Mountains to the southwest and the Clark Mountains to the southeast.
Document 7: Kawich Range: The Kawich Range is a mountain range in Nye County in southern Nevada in the United States, just south of the Hot Creek Range. The southern part of the range lies on the Nellis Air Force Range. The mountains cover an area of about 250 sqmi and contain Kawich Peak, at 9399 ft above sea level. U.S. Route 6 crosses the pass between The Kawich and the Hot Creek ranges and meets State Route 375 at Warm Springs just north of the range. To the east lies the Reveille and Kawich valleys with the Reveille Range to the east of the northern portion and the Belted Range east of Quartzite Mountain at the southern end. The broad Pahute Mesa and Gold Flat lie to the south with Cactus Flat and the Cactus Range to the southwest. To the northwest across Stone Cabin Valley lies the Monitor Range.
Document 8: Yucca Mountain nuclear waste repository: The Yucca Mountain Nuclear Waste Repository, as designated by the Nuclear Waste Policy Act amendments of 1987, is to be a deep geological repository storage facility within Yucca Mountain for spent nuclear fuel and other high level radioactive waste in the United States. The site is located on federal land adjacent to the Nevada Test Site in Nye County, Nevada, about 80 mi northwest of the Las Vegas Valley.
Document 9: Southern Nevada: Southern Nevada (often abbreviated as SNV) is the region of Nevada which includes the Las Vegas Valley. Southern Nevada also includes the areas in and around Tonopah, Hawthorne, Pahrump, and Pioche, though some organizations based in the Las Vegas area (e.g., the Southern Nevada Health District) effectively use the term to refer to Clark County only.
Document 10: Yucca Mountain: Yucca Mountain is a mountain in Nevada, near its border with California, approximately 100 mi northwest of Las Vegas. Located in the Great Basin, Yucca Mountain is east of the Amargosa Desert, south of the Nevada Test and Training Range and in the Nevada National Security Site. It is the site of the Yucca Mountain nuclear waste repository, which is currently identified by Congressional law as the nation's spent nuclear waste storage facility. However, while licensure of the site through the Nuclear Regulatory Commission is ongoing, political maneuvering led to the site being de-funded in 2010.
Document 11: Nevada Test Site: The Nevada National Security Site (N2S2),(though the abbreviation NNSS is still used), previously the Nevada Test Site (NTS), is a United States Department of Energy reservation located in southeastern Nye County, Nevada, about 65 miles (105 km) northwest of the city of Las Vegas. Formerly known as the Nevada Proving Grounds, the site was established on 11 January 1951 for the testing of nuclear devices, covering approximately 1,360 square miles (3,500 km) of desert and mountainous terrain. Nuclear weapons testing at the Nevada Test Site began with a 1-kiloton-of-TNT (4.2 TJ) bomb dropped on Frenchman Flat on 27 January 1951. Many of the iconic images of the nuclear era come from the NTS. NNSS is operated by National Security Technologies, LLC, a joint venture of Northrop Grumman, AECOM, CH2M Hill, and Babcock & Wilcox.
Document 12: Penstemon pahutensis: Penstemon pahutensis is a species of penstemon known by the common name Pahute Mesa beardtongue, or simply Pahute beardtongue. It is native to the desert hills and mountains of southern Nevada, including the Pahute Mesa for which it is named. It can also be found in a few areas over the border in California. It is a perennial herb growing up to 35 cm tall. The paired, narrow leaves are linear to lance-shaped and up to 10 cm long. The inflorescence bears blue-purple flowers up to 3 cm long. The inside of the wide mouth of the flower is lined with white or yellow hairs, and the staminode is coated in yellow hairs.
Document 13: Pahute Mesa (landform): The Pahute Mesa (landform) is a large, 60 mi long mesa in southern Nye County, Nevada. The mesa's southeast region lies in the Nevada Test Site which is southeast; the region in the test site is called Pahute Mesa, one of the major test site sub-regions.
Document 14: Pahute Mesa: Pahute Mesa is one of four major nuclear test regions within the Nevada National Security Site (NNSS). It occupies 243 sqmi in the northwest corner of the NNSS in Nevada. The eastern section is known as Area 19 and the western section as Area 20.
Document 15: Pahranagat National Wildlife Refuge: The Pahranagat National Wildlife Refuge is a protected wildlife refuge, located at the southern end of the Pahranagat Valley and administered by the U.S. Fish and Wildlife Service. It is situated 90 mi north of Las Vegas, Nevada in Lincoln County, Nevada. The 5380 acre refuge was created on August 16, 1963 and is part of the larger Desert National Wildlife Refuge Complex, which also includes the Ash Meadows National Wildlife Refuge, the Desert National Wildlife Refuge, and the Moapa Valley National Wildlife Refuge.
ground_truth: Nevada Proving Grounds