Donkey in the context of "Epona"

The first evidence of horses in warfare dates from Eurasia between 4000 and 3000 BC. A Sumerian illustration of warfare from 2500 BC depicts some type of equine pulling wagons. By 1600 BC, improved harness and chariot designs made chariot warfare common throughout the Ancient Near East, and the earliest written training manual for war horses was a guide for training chariot horses written about 1350 BC. As formal cavalry tactics replaced the chariot, so did new training methods, and by 360 BC, the Greek cavalry officer Xenophon had written an extensive treatise on horsemanship. The effectiveness of horses in battle was also revolutionized by improvements in technology, such as the invention of the saddle, the stirrup, and the horse collar.

Many different types and sizes of horses were used in war, depending on the form of warfare. The type used varied with whether the horse was being ridden or driven, and whether they were being used for reconnaissance, cavalry charges, raiding, communication, or supply. Throughout history, mules and donkeys, as well as horses played a crucial role in providing support to armies in the field.

Nomadic pastoralism, also known as nomadic herding, is a form of pastoralism in which livestock are herded in order to seek for fresh pastures on which to graze. True nomads follow an irregular pattern of movement, in contrast with transhumance, where seasonal pastures are fixed. However, this distinction is often not observed and the term 'nomad' used for both—and in historical cases the regularity of movements is often unknown in any case. The herded livestock include cattle, water buffalo, yaks, llamas, sheep, goats, reindeer, horses, donkeys or camels, or mixtures of species. Nomadic pastoralism is commonly practiced in regions with little arable land, typically in the developing world, especially in the steppe lands north of the agricultural zone of Eurasia. Pastoralists often trade with sedentary agrarians, exchanging meat for grains; however, they have been known to raid.

Of the estimated 30–40 million nomadic pastoralists worldwide, most are found in central Asia and the Sahel region of North and West Africa, such as Fulani, Tuaregs, and Toubou, with some also in the Middle East, such as traditionally Bedouins, and in other parts of Africa, such as Nigeria and Somalia. Increasing numbers of stock may lead to overgrazing of the area and desertification if lands are not allowed to fully recover between one grazing period and the next. Increased enclosure and fencing of land has reduced the amount of land for this practice.

A yoke is a wooden beam used between a pair of oxen or other animals to enable them to pull together on a load when working in pairs, as oxen usually do; some yokes are fitted to individual animals. There are several types of yoke, used in different cultures, and for different types of oxen. A pair of oxen may be called a yoke of oxen, and yoke is also a verb, as in "to yoke a pair of oxen". Other animals that may be yoked include horses, mules, donkeys, and water buffalo.

In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, subspecies, species or genera through sexual reproduction. Generally, it means that each cell has genetic material from two different organisms, whereas an individual where some cells are derived from a different organism is called a chimera. Hybrids are not always intermediates between their parents such as in blending inheritance (a now discredited theory in modern genetics by particulate inheritance), but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are.

Species are reproductively isolated by strong barriers to hybridization, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo. Some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering times, pollen vectors, inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and the structure of the chromosomes. A few animal species and many plant species, however, are the result of hybrid speciation, including important crop plants such as wheat, where the number of chromosomes has been doubled.

A pack animal, also known as a sumpter animal or beast of burden, is a working animal used to transport goods or materials by carrying them, usually on its back.

Domestic animals of many species are used in this way, among them alpacas, Bactrian camels, donkeys, dromedaries, gayal, goats, horses, llamas, mules, reindeer, water buffaloes and yaks.

The mule is a domestic equine hybrid between a donkey and a horse. It is the offspring of a male donkey (a jack) and a female horse (a mare). The horse and the donkey are different species, with different numbers of chromosomes; of the two possible first-generation hybrids between them, the mule is easier to obtain and more common than the hinny, which is the offspring of a male horse (a stallion) and a female donkey (a jenny).

Mules vary widely in size, and may be of any color seen in horses or donkeys. They are more patient, hardier and longer-lived than horses, and are perceived as less obstinate and more intelligent than donkeys.

Naqa or Naga'a (Meroitic: 𐦶𐦬𐦲𐦵‎, romanized: Tolakate; Arabic: ٱلـنَّـقْـعَـة, romanized: An-Naqʿah) is a ruined ancient city of the Kushite Kingdom of Meroë in modern-day Sudan. The ancient city lies about 170 km (110 miles) north-east of Khartoum, and about 50 km (31 miles) east of the Nile River located at approximately MGRS 36QWC290629877. Here smaller wadis meet the Wadi Awateib coming from the center of the Butana plateau region, and further north at Wad ban Naqa from where it joins the Nile. Naqa was only a camel or donkey's journey from the Nile, and could serve as a trading station on the way to the east; thus it had strategic importance.

Naqa is one of the largest ruined sites in the country and indicates an important ancient city once stood in the location. It was one of the centers of the Kingdom of Meroë, which served as a bridge between the Mediterranean world and Africa. The site has two notable temples, one devoted to Amun and the other to Apedemak which also has a Roman kiosk nearby. With Meroë and Musawwarat es-Sufra it is known as the Island of Meroe, and was listed as a UNESCO World Heritage Site in 2011.

Buridan's ass is an illustration of a paradox in philosophy in the conception of free will. It refers to a hypothetical situation wherein an ass (or donkey) that is equally hungry and thirsty is placed precisely midway between a stack of hay and a pail of water. Since the paradox assumes the ass will always go to whichever is closer, it dies of both hunger and thirst since it cannot make any rational decision between the hay and water. A common variant of the paradox substitutes the hay and water for two identical piles of hay; the ass, unable to choose between the two, dies of hunger.

The paradox is named after the 14th-century French philosopher Jean Buridan, whose philosophy of moral determinism it satirizes. Although the illustration is named after Buridan, philosophers have discussed the concept before him, notably Aristotle, who put forward the example of a man equally hungry and thirsty, and Al-Ghazali, who used a man faced with the choice of equally good dates.