Religion in the Mongol Empire
Mongols were highly tolerant of most religions, and typically sponsored several at the same time. At the time of Genghis Khan in the 13th century, virtually every religion had found converts, from Buddhism to Christianity and Manichaeanism to Islam. To avoid strife, Genghis Khan set up an institution that ensured complete religious freedom, though he himself was a shamanist. Under his administration, all religious leaders were exempt from taxation, and from public service. Mongol emperors were known for organizing competitions of religious debates among clerics, and these would draw large audiences.
Initially there were few formal places of worship, because of the nomadic lifestyle. However, under Genghis's successor Ögedei, several building projects were undertaken in he Mongol capital of Karakorum. Along with palaces, Ogedei built houses of worship for the Buddhist, Muslim, Christian, and Taoist followers. The dominant religions at that time were Shamanism, Tengriism and Buddhism, although Ogodei's wife was a Christian. In later years of the empire, three of the four principal khanates embraced Islam, as Islam was favored over other religions. The Yuan Dynasty mainly adopted Tibetan Buddhism while there were other religions practiced in the east of the Mongol Empire.
Buddhists entered the service of Mongol Empire in the early 13th century. Buddhist monasteries established in Karakorum were granted tax exempt status, though the religion was not given official status by the Mongols until later. All variants of Buddhism, such as Chinese, Tibetan and Indian Buddhism flourished, though Tibetan Buddhism was eventually favored at the imperial level under emperor Mongke, who appointed Namo from Kashmir as chief of all Buddhist monks.
Ogedei's son and Guyuk's younger brother, Khoten, became the governor of Ningxia and Gansu. He launched a military campaign into Tibet under the command of Generals Lichi and Dhordha, and the marauding Mongols burned down Tibetan monuments such as the Reting monastery and the Gyal temple in 1240. Prince Kötön was convinced that no power in the world exceeded the might of the Mongols. However, he also believed that religion was necessary in the interests of the next life. Thus he invited Sakya Pandita to his ordo. Prince Kötön was impressed and healed by Sakya Pandita's teachings and knowledge, and later became the first known Buddhist prince of Mongol empire.
Kublai, the founder of Yuan Dynasty, also favored Buddhism. As early as the 1240s, he made contacts with a Chan Buddhist monk Haiyun, who became his Buddhist adviser. Kublai's second son, whom he later officially designated as his successor in the Yuan Dynasty, was given a Chinese name "Zhenjin" (literally, "True Gold") by Haiyun. Khatun Chabi influenced Kublai to be converted to Buddhism, as she had received the Hévajra tantra initiations from Phagspa and been impressed. Kublai appointed Phagspa his state preceptor, and later imperial preceptor, giving him power over all the Buddhist monks within the territory of the Yuan Dynasty. For the rest of the Yuan Dynasty in Mongolia and China, until the Mongols were overthrown in 1368, Tibetan lamas were the most influential Buddhist clergy. Via the Tibetan clergy, Indian Buddhist textual tradition strongly influenced the religious life in the Empire.
Some of the Ilkhans in Iran held Paghmo gru-pa order as their appanage in Tibet and lavishly patronized a variety of Indian, Tibetan and Chinese Buddhist monks. But in 1295, Ghazan persecuted Buddhists and destroyed their temples. Before his conversion to Islam though, he had built a Buddhist temple in Khorasan. The 14th century Buddhist scriptures found at archaeological sites related to Chagatai Khanate show the popularity of Buddhism among the Mongols and the Uighurs. Tokhta of Golden Horde also encouraged lamas to settle in Russia  But his policy was halted by his successor Ozbeg Khan, a Muslim.
Some Mongols had been evangelized by Christian Nestorians since about the 7th century, and a few Mongols were converted to Catholicism, esp. by John of Montecorvino who was appointed by the Papal states of Europe.
The religion never achieved a great position in the Mongol Empire, but many Great Khans and lesser leaders were raised by Christian mothers and educated by Christian tutors. Some of the major Christian figures among the Mongols were: Sorghaghtani Beki, daughter in law of Genghis Khan, and mother of the Great Khans Möngke, Kublai, Hulagu and Ariq Boke; Sartaq, khan of Golden Horde; Doquz Khatun, the mother of the ruler Abaqa; Kitbuqa, general of Mongol forces in the Levant, who fought in alliance with Christians. Marital alliances with Western powers also occurred, as in the 1265 marriage of Maria Palaiologina, daughter of Emperor Michael VIII Palaeologus, with Abaqa. Tokhta, Oljeitu and Ozbeg had Greek Khatuns as well. The Mongol Empire contained the lands of the Eastern Orthodox Church in Caucasus and Russia, the Apostolic church in Armenia and the Assyrian Church of Nestorians in Central Asia and Persia.
The 13th century saw attempts at a Franco-Mongol alliance with exchange of ambassadors and even military collaboration with European Christians in the Holy Land. Ilkhan Abagha sent a tumen to support crusaders during the Ninth Crusade in 1271. The Nestorian Mongol Rabban Bar Sauma visited some European courts in 1287-1288. At the same time however, Islam began to take firm root amongst the Mongols, as those who embraced Christianity such as Tekuder, became Muslim. After Ongud Mar Yahbh-Allaha, the monk of Kublai Khan, was elected a catholicos of the eastern Christian church in 1281, Catholic missionaries were begun to sent to all Mongol capitals.
The Ilkhanate, Golden Horde, and the Chagatai Khanate - three of the four principal khanates - embraced Islam, as the Mongol elite favored Islam to strengthen their rule over the Muslim majority populace. Non-Muslim Mongols also employed many Muslims in various fields and increasingly took their advice in administrative affairs. For example, Genghis Khan's advisor, Mahmud Yalavach, and Kublai Khan's financial minister, Ahmad Fanakati, were Muslims. Still the mainlands of the Mongols remained staunchly Buddhist and Shamans.
As they were well educated and knew Turkish and Mongolian, Muslims became a favored class of officials with notable Mongol converts to Islam including Mubarak Shah and Tarmashirin of the Chagatai Khanate, Tuda Mengu and Negudar of the Golden Horde, Ghazan and Öljaitü of the Ilkhanate. Berke, who ruled Golden Horde from 1257 to 1266, was the first Muslim leader of any Mongol khanates. Ghazan was the first Muslim khan to adopt Islam as national religion of Ilkhanate, followed by Uzbek of the Golden Horde who urged his subjects to accept the religion as well. Ghazan continued his non-Muslim forefathers' approach toward religious tolerance. When Ghazan learned that some Buddhist monks feigned conversion to Islam due to the earlier destruction of some of their temples, he granted permission to all who wished to return to Tibet where they could freely follow their faith and be among other Buddhists.
Though in Chagatai Khanate, Buddhism and Shamanism flourished until the 1350s. When the western part of the khanate embraced Islam quickly, the eastern part or Moghulistan slowed Islamization until Tughlugh Timur (1329/30-1363) who accepted Islam with his thousands of subjects.
The Yuan Dynasty, unlike the western khanates, never converted to Islam. The other three Khanates accepted the suzerainty of Yuan dynasty but gradually that withered away. There had been many Muslim residing in Yuan Dynasty territory since Kublai Khan and his successors were tolerant of other religions. Nevertheless, Buddhism was the most influential religion within its territory. Contact between Yuan emperors in China and states in North Africa, India and Middle East lasted until the mid-14th century. Muslims were classified as Semuren, "various sorts", below the Mongols but above the Chinese.
Shamanism, which practices a form of animism with several meanings and with different characters, was a popular religion in ancient Central Asia and Siberia. The central act in the relationship between human and nature was the worship of the Blue Mighty Eternal Heaven - "Blue Sky" (Хөх тэнгэр, Эрхэт мөнх тэнгэр). Chingis Khan showed his spiritual power was greater than others and himself to be a connector to heaven after the execution of rival shaman Teb Tengri Kokhchu.
Under the Mongol Empire the khans such as Batu, Duwa, Kebek and Tokhta kept a whole college of male shamans. Those shamans were divided into bekis and others. The bekis (not confused with princess) were camped in front of the Great Khan's palace while some shamans left behind it. In spite of astrological observations and regular calendar ceremonies, Mongol shamans led armies and performed weather magic (zadyin arga). Shamans played a powerful political role behind the Mongol court.
While Ghazan converted to Islam, he still practiced some elements of Mongol shamanism. The Yassa code remained in place and Mongol shamans were allowed to remain in the Ilkhanate empire and remained politically influential throughout his reign as well as Oljeitu's. However, ancient Mongol shamanistic traditions went into decline with the demise of Oljeitu and with the rise of rulers practicing a purified form of Islam. With Islamization the shamans were no longer important as had been they in Golden Horde and Ilkhanate. But they still performed in ritual ceremonies alongside the Nestors and Buddhist monks in Yuan Dynasty.
Religion under Genghis Khan
As Genghis Khan united the Mongol tribes and raged war on most of Asia he became known as one of the most ruthless and brutal warlords of all time. However one hallmark during his military conquest was his tolerance of all religions. He embraced diversity and decreed religious freedom for everyone. Genghis Khan’s tolerance proved to be beneficial for him. As European princes expelled some of their most skilled non-Christian subjects, the Mongols welcomed these beneficial others, blind to religion. Khan continued to use religious persecution to his benefit. He would use suppressed people as spies in cities such as Bagdad and then take the land assimilating all those willing. In her book Day of Empire, Amy Chua claims that “the Mongols were more religiously open than any other power in the world.”
Genghis Khan’s Inner Circle
After a failed assassination attempt Genghis Khan and 20 of his men fled and nearly starved to death. While on the run these men swore allegiance to one another and remarkably these men included Buddhists, Christians, Muslims, and animists who worshiped the Eternal Blue Sky and the God Mountain of Burkhan Khaldun.
Defender of Religions
When Muslim envoys came from central Asia to seek Genghis Khan’s protection from the religious persecution they faced under their Christian khan Guchlug, Genghis Khan was happy to help. He led a campaign into Balasagun and killed Guchlug and declared religious freedom in all his lands. This earned Genghis Khan the title as "defender of religions" and it was even said he was "one of the mercies of the Lord and one of the bounties of his divine grace."
The Mongols passion for religious tolerance appealed to writers of the eighteenth century. "The Catholic inquisitors of Europe", wrote Edward Gibbon in a celebrated passage, "who defended nonsense by cruelty, might have been confounded by the example of a barbarian, who anticipated the lessons of philosophy and established by his laws a system of pure theism and perfect toleration." He goes on to add, in a footnote, "a singular conformity may be found between the religious laws of Zingis Khan and of Mr Locke."
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