The Mongol religion was based on a deep respect for and fear of nature; not surprising considering the fact that they lived virtually at the mercy of nature. They were subject to severe fluctuations of temperature, winds that howled down out of the Siberian plain, the land of evil gods, kanun kotan and periods of drought alternating with drowning rains. Since the early Mongols lived their whole lives on the open steppe, the sky and the heavenly bodies were objects of awe and reverence. They worshiped the Everlasting Blue Sky, mongke tengri, controller of the evil forces; the stars, and the moon, and they genuflected nine times before the sun, naran at dawn. Since rivers, homes of both good and evil spirits, kelets, were considered sacred, Mongols refrained from polluting them; never washing or urinating in them. The earth was evil, and in its eternal darkness and cold dwelt the god, Erlik Khan. They addressed prayers to their gods and honored them with offerings. They had no altars or temples; preferring to worship out in the open. Sometimes sacrifices were made at cairns of stones, and on hills which offered an uninterrupted view of the Eternal Blue Sky.

Before going on a campaign, Jenghiz Khan had been known to climb the sacred mountain, Burqan-qaldun, face the sun, hang his belt around his neck, take off his hat, (an act of submission), strike his breast, genuflect nine times, pour out an offering of mare's milk, and pray that Tengri would grant him success in the coming battle. After a victory, thanks would be offered to Tengri and to the "earth mother" eke-otuken.

Venerating the sun was part of the cult of the Eternal Blue Sky. Homage paid to Burqan-qaldun was part of the cult of the Altaic people in general.

The Mongols worshiped fire considering it a purifying element. They never burned trash and would not pass a knife through flames because it might behead the flames, thus taking away their power. In their tents they had idols representing the various gods that protected them. At meals they fed each god by rubbing meat and broth over its mouth. The number of gods was virtually infinite, denoting a universal supernatural presence. Felt idols, made in the image of man, were hung on either side of the door. Below these, for instance, they might put a felt model of an udder, believing that this guardian spirit would protect their cattle. Some idols were made from silk and these were devoutly worshiped. They were placed in beautiful covered carts outside the doors of their tents. If anyone stole anything from these wagons, he was put to death immediately. The ladies of the camp gathered to make idols, which was done reverently, and when they were finished, they would take a sheep, eat it and burn its bones in a fire. When a child was ill they made an idol and fastened it over his bed. When they killed an animal they offered its heart to the idol in the cart, and in the morning they would remove it, cook and eat it. If an animal offering was slaughtered for food, they would not break any of its bones but burn them in a fire.

The shamans, priest of the Mongols, held positions of great honor in Mongol society. They communed with the gods and the spirits of the dead, going into trances and speaking with the voices of the dead. Through this ritual they conducted the deceased's spirit to the underworld. Before conducting any important business the khans would consult a shaman, who would speak to the gods and relay their messages to the khan. Because of their important position the shamans gained great secular power.

The Mongols were afraid of lightning. During a storm with lightning, they would turn all strangers out of their tents, and wrapped in black felt, would hide until the storm passed. When a person died, the relatives of the person and anyone else living in his tent had to be purified by fire. Two fires were lit and near these, two lances were stuck in the ground. A rope was stretched between the points of the lances with a few rags tied on it, the rags representing idols. The people and their possessions must pass under this cord and between the two fires. Two women, standing on each side, sprinkled water and recited charms. During the process whatever fell to the ground was taken by the exorcists. If anyone were killed by lightning, all the people living in his tent must pass between the fires in the same way. The tent and possessions of the dead person were rejected as unclean and no one ever dared touch them again. Immolation of wives, servants and horses belonging to a chief was still practiced by the Jenghiz-kanid Mongols.

Although they had no religious code to live by, they had certain traditions, and according to these, certain actions were considered sinful. It was a sin to poke the fire or touch the fire in any way with a dagger. To take meat from a kettle with a dagger, or to hack meat with a hatchet near a fire was a sin. They believed this would take the force from the fire. It was sinful to lean on a whip used to beat horses or to touch arrows with the whip. To catch or kill young birds, to strike a horse with the rein, or to break one bone with the help of another, were all considered sinful. In addition, it was sinful to pour milk or other liquids on the ground or to uninate in a tent. For the latter, the penalty was death. If a person took food in his mouth and was unable to swallow it, but spit it out, they dug a hole under the tent and dragged the person through it, then killed him. Death was the penalty for adultery and fornication. Anyone who stepped on the threshold of a chief or khan was killed. They believed after death they would live in another world, where they would breed cattle, drink, eat and live in the same way they did during their lifetime.

A Mongol man had as many wives as he could keep. The early Mongols were exogamous, not marrying within their tribe. They often resorted to kidnapping in order to get a wife. This wifenapping led to internecine wars on the steppe. During Jenghiz Khan's time marriage customs changed. A son could marry his dead father's wives, other wives were bought or captured in wars. Eventually they were allowed to marry all their relatives except their own mother, their own daughter, and their sisters by the same mother. On the death of a brother, a younger brother or another younger member of the family might marry the widow. Many widows did not remarry, saving themselves to join their husband in the afterlife.

When a father arranged for the marriage of a daughter, he prepared a feast, and the daughter ran away to relatives where she hid. The father would give his daughter to the groom and instruct him to take her, wherever she was hiding. When the groom found the bride, he and his friends who helped him in the search, would take her by mock force to his tent.

Polygamy and concubinage were common, and were characteristic of nomadic people. Children of the concubines were considered legitimate. The seniority of the children was determined by the status of the wives; the first wife usually being the senior wife. As to inheritance, the eldest son received more than the younger sons. The youngest son inherited the house of his father with all the belongings, including his wives. Jenghiz Khan's youngest son, Tolui, not only inherited his father's household but also the homeland of the Mongols. Unfaithfulness in either husband or wife was punishable by death.

Another custom was marriages between dead children. If a man had a son who had died and another had a daughter of a suitable age for his son, and she too had died, a marriage was arranged between these two at a time when the son would have reached a marriageable age. Documents were drawn up including the dowry. These documents were burned and as the smoke arose the news of the marriage was carried to the dead couple, who then considered themselves married. A wedding feast would be held; some of the food would be scattered around so the bride and groom, in the other world, share the wedding feast. Images of the bride and groom were made and put on a richly decorated cart. The cart, drawn by horses, was led throughout the area with a great deal of celebrating. The images were burnt, and prayers were offered to the gods, who would carry the news of the marriage to the other world. The parents drew and painted images of slaves, horses, other animals, clothing, furniture and household utensils they would have given for dowries. These were burned and the people believed their children would have these things in the other world. The parents and the kinsmen of the dead considered themselves related for as long as they lived. Before the Mongols employed Chinese and Persian physicians to travel with their armies, their medical practices were quite primitive. Because arrows were often poisoned, it was customary to suck the clotted blood from wounds, and hopefully the poison also. Frequently the blood-sucking lasted for hours until the wounded person revived and asked for something to drink. He was given a cup of qumiz, and if circumstances permitted, the wound was cauterized after the sucking procedure. Since there were no physicians, each warrior had to depend on his brother-in-arms to take care of him.

When a person became ill, a lance wrapped in black felt, was planted in front of his dwelling. No stranger dared step across the threshold. When he was about to die, almost everyone left, for those who stayed would not be allowed to enter the camp of a Khan or the Great Khan until the ninth month. If the dead person were of high rank, he might be buried in the steppe at a place he had chosen prior to his death. He would be buried seated in the middle of his tent, with a table in front of him. On this table a bowl of meat and a jug of qumiz would be placed. Gold and silver might also be put in the grave. A mare and her foal were buried, along with a saddled and bridled horse. Another horse was eaten at the burial feast, its skin was stuffed with straw; and then impaled on a tall pole, it was raised above the grave. Thus when the person arrived in the other world, he had his tent, a mare for milk and to start a new herd, and a horse to ride. The bones of the horse eaten at the burial feast were burnt for the good of the soul of the dead man. For three generations no one was allowed to mention the dead person's name.

Some members of the nobility were buried in another way. A grave was dug in a secret place in the steppe. The favorite slave of the dead man was placed live, underneath the corpse. When the slave was nearly dead, he would be taken out, revived, and reinterred. This process was repeated three times. If the slave survived, he was given his freedom and was treated with respect by the relatives of the dead man.

Humanity is possessed of both good and bad traits and the Mongols were no exception. Probably their most outstanding good trait was their complete and ready obedience to their masters. The Mongols respected their leaders and did not readily lie to them. They rarely ever argued with each other and murder or wounding were rare. Petty theft might occur but robbery on a large scale was not found among them. Their tents and the carts where they kept their valuables were not locked. They showed respect for one another, were friendly and willing to share their food with each other, even though it often was scarce. They could go without food for several days without complaining. The will to survive was extremely strong however; and if necessary they would eat mice, dead animals they found; even their own dogs and cats if times were bad enough. And they often were bad. They were not fond of luxury, nor envious of one another. The women were chaste and had good reputations; however, they were known to use vulgar and offensive language playfully. It was easy to see the effect of the Great Yassa of Jenghiz Khan on the people.

They were arrogant toward other people, looking down on them no matter whether they were of noble or base birth. They would walk in front of a foreign noble whom they had been assigned to look after. They showed quick anger and impatience with foreigners and were known to lie to them. They have been described as being sly, deceitful and cunning. If they intended to harm someone, their plan was kept secret so the enemy could not build a defense against it. Drunkenness was an accepted practice and if anyone drank too much, he vomited on the spot and went right on with his drinking. Toward others they were greedy and fiercely held on to what they had. Killing other people was considered to be of little consequence. To be fair to the Mongols, it must be noted that the foregoing traits were observed and recorded by several European monks.

The Mongols observed a strict order of seating in their tents. The seat of honor, given to a guest, was beside the master of the house who sat in the center of the tent near the fire. At the back and to the right, the lady of the house would sit with her children. Toward the end of the thirteenth century, women were permitted to sit closer to the fire to the right of the master. The steppe aristocracy hunted small game with hawks and peregrine falcons. To hunt antelope, they used eagles which hovered over the animals, beating the air lustily. This hovering and beating confused the antelope and kept them occupied until the hunters could loose their arrows and bring the animals down. The Great Hunt, often used as military training, looked good in theory, but due mostly to the terrain, was difficult to carry out. First a large outer circle, nerkeh, was marked out, and the hunters were arranged around this ring. They were placed close together so none of the game could escape. As they slowly closed in toward the middle, the game was driven before them, a maneuver called battue. When all the game had been driven into an inner ring gerkeh, the kill would begin. If the Khan were present, the honor of the first kill went to him.

There was a spirit of good will among the hunters of the steppe. An unwritten law, shiralgha, gave the right to any man who met a hunter who had just killed an animal, to claim a portion of that animal if it had not yet been cut up.

Mongol law had its roots in the organization, administration and court of the clan. It developed from the basic needs of the nomadic hunters and cattlebreeders, who had by comparison a rather poor cultural inheritance. The Yassa of Jenghiz Khan was the best known, the oldest, and also the most important Mongol code of laws. It was compiled between 1206 and 1218, the first decade of the reign of Jenghiz Khan as Emperor of the Steppes.

Family organization of the nomadic Mongol society was patriarchal. The father and husband had a great deal of power and authority within his family. There was, however, a certain amount of respect shown to the wife's or mother's clan.

The scattered Mongol tribes, at first, regulated their lives according to local custom. At the beginning of the thirteenth century, these tribes were united under the rule of Jenghiz Khan. With this union came also the union of customary law, which became written law for all the Mongols under the sovereignty of Jenghiz Khan, and was known as the Great Yassa. It was called "Great" because it was the law common to all the tribes as opposed to an individual tribal Yassa which could exist independent of and side by side with the Great Yassa.

Most of the provisions of the Yassa were punitive in nature; to insure the execution of the Khan's orders, the observance of the Yassa, the carrying out of military orders, and adherence to Mongol custom.