The pastoral societies that stretched across Eurasia had the great military advantage of being able to raise horses in large numbers and support themselves from their flocks of sheep, goats, and other animals. Nomadic pastoralists generally were organized on the basis of clans and tribes that selected chiefs for their military talent. Much of the time these tribes fought with each other, but several times in history leaders formed larger confederations capable of coordinated attacks on cities and towns.

From the fifth to the twelfth centuries the most successful nomadic groups on the Eurasian steppes were Turks who gained ascendancy in many of the societies from the Middle East to northern India. In the early thirteenth century, the Mongol leader Chinggis Khan conquered much of Eurasia.

After Chinggis’s death, the empire was divided into four khanates ruled by four of Chinggis’s descendants. For a century the Mongol Empire fostered unprecedented East-West contact. They encouraged trade and often moved craftsmen and other specialists from one place to another. The Mongols were tolerant of other religions. As more Europeans made their way east, Chinese inventions such as printing and the compass made their way west. Europe especially benefited from the spread of technical and scientific ideas. Diseases also spread, including the Black Death.

India was invaded by the Mongols but not conquered. After the fall of the Gupta Empire in about 480, India was for the next millennium ruled by small kingdoms, which allowed regional cultures to flourish. For several centuries Muslim Turks formed the Delhi sultanate in north India. Over time Islam gained adherents throughout South Asia. Hinduism continued to flourish, but Buddhism declined.

Throughout the medieval period India continued to be the center of active seaborne trade, and this trade helped carry Indian ideas and practices to Southeast Asia. Local rulers used experts from India to establish strong states, such as the Khmer kingdom and the Srivijayan kingdom. Buddhism became the dominant religion throughout the region, though Hinduism also played an important role. The Pacific islands east of Indonesia remained isolated culturally for centuries.