Question: What is a staple food in the area of Tangs biggest rival?

full_context: Document 1: Sino-Tibetan relations during the Ming dynasty: Discussions of strategy in the mid Ming dynasty focused primarily on recovery of the Ordos region, which the Mongols used as a rallying base to stage raids into Ming China. Norbu states that the Ming dynasty, preoccupied with the Mongol threat to the north, could not spare additional armed forces to enforce or back up their claim of sovereignty over Tibet; instead, they relied on "Confucian instruments of tribute relations" of heaping unlimited number of titles and gifts on Tibetan lamas through acts of diplomacy. Sperling states that the delicate relationship between the Ming and Tibet was "the last time a united China had to deal with an independent Tibet," that there was a potential for armed conflict at their borders, and that the ultimate goal of Ming foreign policy with Tibet was not subjugation but "avoidance of any kind of Tibetan threat." P. Christiaan Klieger argues that the Ming court's patronage of high Tibetan lamas "was designed to help stabilize border regions and protect trade routes."
Document 2: Tibet: The economy of Tibet is dominated by subsistence agriculture, though tourism has become a growing industry in recent decades. The dominant religion in Tibet is Tibetan Buddhism; in addition there is Bön, which is similar to Tibetan Buddhism, and there are also Tibetan Muslims and Christian minorities. Tibetan Buddhism is a primary influence on the art, music, and festivals of the region. Tibetan architecture reflects Chinese and Indian influences. Staple foods in Tibet are roasted barley, yak meat, and butter tea.
Document 3: Tibet: Muslims have been living in Tibet since as early as the 8th or 9th century. In Tibetan cities, there are small communities of Muslims, known as Kachee (Kache), who trace their origin to immigrants from three main regions: Kashmir (Kachee Yul in ancient Tibetan), Ladakh and the Central Asian Turkic countries. Islamic influence in Tibet also came from Persia. After 1959 a group of Tibetan Muslims made a case for Indian nationality based on their historic roots to Kashmir and the Indian government declared all Tibetan Muslims Indian citizens later on that year. Other Muslim ethnic groups who have long inhabited Tibet include Hui, Salar, Dongxiang and Bonan. There is also a well established Chinese Muslim community (gya kachee), which traces its ancestry back to the Hui ethnic group of China.
Document 4: Tibet: The main crops grown are barley, wheat, buckwheat, rye, potatoes, and assorted fruits and vegetables. Tibet is ranked the lowest among China’s 31 provinces on the Human Development Index according to UN Development Programme data. In recent years, due to increased interest in Tibetan Buddhism, tourism has become an increasingly important sector, and is actively promoted by the authorities. Tourism brings in the most income from the sale of handicrafts. These include Tibetan hats, jewelry (silver and gold), wooden items, clothing, quilts, fabrics, Tibetan rugs and carpets. The Central People's Government exempts Tibet from all taxation and provides 90% of Tibet's government expenditures. However most of this investment goes to pay migrant workers who do not settle in Tibet and send much of their income home to other provinces.
Document 5: Sino-Tibetan relations during the Ming dynasty: Laird writes that the Ming appointed titles to eastern Tibetan princes, and that "these alliances with eastern Tibetan principalities are the evidence China now produces for its assertion that the Ming ruled Tibet," despite the fact that the Ming did not send an army to replace the Mongols after they left Tibet. Yiu Yung-chin states that the furthest western extent of the Ming dynasty's territory was Gansu, Sichuan, and Yunnan while "the Ming did not possess Tibet."
Document 6: Sino-Tibetan relations during the Ming dynasty: During the Five Dynasties and Ten Kingdoms period of China (907–960), while the fractured political realm of China saw no threat in a Tibet which was in just as much political disarray, there was little in the way of Sino-Tibetan relations. Few documents involving Sino-Tibetan contacts survive from the Song dynasty (960–1279). The Song were far more concerned with countering northern enemy states of the Khitan-ruled Liao dynasty (907–1125) and Jurchen-ruled Jin dynasty (1115–1234).
Document 7: Sino-Tibetan relations during the Ming dynasty: Tibet was once a strong power contemporaneous with Tang China (618–907). Until the Tibetan Empire's collapse in the 9th century, it was the Tang's major rival in dominating Inner Asia. The Yarlung rulers of Tibet also signed various peace treaties with the Tang, culminating in a treaty in 821 that fixed the borders between Tibet and China.
Document 8: Tibet: The Tibetan Empire emerged in the 7th century, but with the fall of the empire the region soon divided into a variety of territories. The bulk of western and central Tibet (Ü-Tsang) was often at least nominally unified under a series of Tibetan governments in Lhasa, Shigatse, or nearby locations; these governments were at various times under Mongol and Chinese overlordship. The eastern regions of Kham and Amdo often maintained a more decentralized indigenous political structure, being divided among a number of small principalities and tribal groups, while also often falling more directly under Chinese rule after the Battle of Chamdo; most of this area was eventually incorporated into the Chinese provinces of Sichuan and Qinghai. The current borders of Tibet were generally established in the 18th century.
Document 9: Sino-Tibetan relations during the Ming dynasty: The Ming initiated sporadic armed intervention in Tibet during the 14th century, but did not garrison permanent troops there. At times the Tibetans also used armed resistance against Ming forays. The Wanli Emperor (r. 1572–1620) made attempts to reestablish Sino-Tibetan relations after the Mongol-Tibetan alliance initiated in 1578, which affected the foreign policy of the subsequent Qing dynasty (1644–1912) of China in their support for the Dalai Lama of the Gelug school. By the late 16th century, the Mongols were successful armed protectors of the Gelug Dalai Lama, after increasing their presence in the Amdo region. This culminated in Güshi Khan's (1582–1655) conquest of Tibet from 1637–1642 and the establishment of the Ganden Phodrang regime by the 5th Dalai Lama with his help.
Document 10: Tibet: In 821/822 CE Tibet and China signed a peace treaty. A bilingual account of this treaty, including details of the borders between the two countries, is inscribed on a stone pillar which stands outside the Jokhang temple in Lhasa. Tibet continued as a Central Asian empire until the mid-9th century, when a civil war over succession led to the collapse of imperial Tibet. The period that followed is known traditionally as the Era of Fragmentation, when political control over Tibet became divided between regional warlords and tribes with no dominant centralized authority.
Document 11: Sino-Tibetan relations during the Ming dynasty: Patricia Ebrey writes that Tibet, like Joseon Korea and other neighboring states to the Ming, settled for its tributary status while there were no troops or governors of Ming China stationed in its territory. Laird writes that "after the Mongol troops left Tibet, no Ming troops replaced them." Wang and Nyima state that, despite the fact that the Ming refrained from sending troops to subdue Tibet and refrained from garrisoning Ming troops there, these measures were unnecessary so long as the Ming court upheld close ties with Tibetan vassals and their forces. However, there were instances in the 14th century when the Hongwu Emperor did use military force to quell unrest in Tibet. John D. Langlois writes that there was unrest in Tibet and western Sichuan, which the Marquis Mu Ying (沐英) was commissioned to quell in November 1378 after he established a Taozhou garrison in Gansu. Langlois notes that by October 1379, Mu Ying had allegedly captured 30,000 Tibetan prisoners and 200,000 domesticated animals. Yet invasion went both ways; the Ming general Qu Neng, under the command of Lan Yu, was ordered to repel a Tibetan assault into Sichuan in 1390.
Document 12: Tibet: Tibet has various festivals that are commonly performed to worship the Buddha[citation needed] throughout the year. Losar is the Tibetan New Year Festival. Preparations for the festive event are manifested by special offerings to family shrine deities, painted doors with religious symbols, and other painstaking jobs done to prepare for the event. Tibetans eat Guthuk (barley noodle soup with filling) on New Year's Eve with their families. The Monlam Prayer Festival follows it in the first month of the Tibetan calendar, falling between the fourth and the eleventh days of the first Tibetan month. It involves dancing and participating in sports events, as well as sharing picnics. The event was established in 1049 by Tsong Khapa, the founder of the Dalai Lama and the Panchen Lama's order.
Document 13: Tuva: Two religions are widespread among the people of Tuva: Tibetan Buddhism and shamanism. Tibetan Buddhism's present-day spiritual leader is Tenzin Gyatso, the fourteenth Dalai Lama. In September 1992, the fourteenth Dalai Lama visited Tuva for three days. On September 20, he blessed and consecrated the new yellow-blue-white flag of Tuva, which had been officially adopted three days previously.The Tuvan people – along with the Yellow Uyghurs in China – are one of the only two Turkic groups who are mainly adherents to Tibetan Buddhism, combined with native shamanism.During the 16th and 17th centuries, Tibetan Buddhism gained popularity in Tuva. An increasing number of new and restored temples are coming into use, as well as novices being trained as monks and lamas. Religious practice declined under the restrictive policies of the Soviet period but is now flourishing.Shamanism is being revived as well, also in organized Tengrian forms.
Document 14: Tibet: Religion is extremely important to the Tibetans and has a strong influence over all aspects of their lives. Bön is the ancient religion of Tibet, but has been almost eclipsed by Tibetan Buddhism, a distinctive form of Mahayana and Vajrayana, which was introduced into Tibet from the Sanskrit Buddhist tradition of northern India. Tibetan Buddhism is practiced not only in Tibet but also in Mongolia, parts of northern India, the Buryat Republic, the Tuva Republic, and in the Republic of Kalmykia and some other parts of China. During China's Cultural Revolution, nearly all Tibet's monasteries were ransacked and destroyed by the Red Guards. A few monasteries have begun to rebuild since the 1980s (with limited support from the Chinese government) and greater religious freedom has been granted – although it is still limited. Monks returned to monasteries across Tibet and monastic education resumed even though the number of monks imposed is strictly limited. Before the 1950s, between 10 and 20% of males in Tibet were monks.
Document 15: Tibet: The most important crop in Tibet is barley, and dough made from barley flour—called tsampa—is the staple food of Tibet. This is either rolled into noodles or made into steamed dumplings called momos. Meat dishes are likely to be yak, goat, or mutton, often dried, or cooked into a spicy stew with potatoes. Mustard seed is cultivated in Tibet, and therefore features heavily in its cuisine. Yak yogurt, butter and cheese are frequently eaten, and well-prepared yogurt is considered something of a prestige item. Butter tea is very popular to drink.
ground_truth: yak meat
sub_queries: Who was the Tangs biggest rival? Answer: Tibet
What is a staple food in Tibet ? Answer: yak meat