Agrarian society
Agrarian society were preceded by hunter and gatherer and horticultural societies and transition into industrial society. The transition to agriculture, called the Neolithic Revolution, has taken place independently multiple times. Horticulture and agriculture as types of subsistence developed among humans somewhere between 10,000 and 8,000 years ago in the Fertile Crescent region of the Middle East. The reasons for the development of agriculture are debated but may have included climate change, and the accumulation of food surplus for competitive gift-giving. Most certainly there was a gradual transition from hunter-gatherer to agricultural economies after a lengthy period when some crops were deliberately planted and other foods were gathered from the wild. In addition to the emergence of farming in the Fertile Crescent, agriculture appeared in: by at least 6,800 B.C.E. in East Asia (rice) and, later, in Central and South America (maize and squash). Small-scale agriculture also likely arose independently in early Neolithic contexts in India (rice) and Southeast Asia (taro). However, full dependency on domestic crops and animals, when wild resources contributed a nutritionally insignificant component to the diet, did not occur until the Bronze Age.
Early Middle Ages
The Romans had practiced two-field agriculture, with a crop grown in one field and the other left fallow and ploughed under to eliminate weeds. Systematic agriculture largely disappeared and yields declined. It is estimated that the Plague of Justinian which began in 541 and recurred periodically for 150 years thereafter killed as many as 100 million people across the world. Some historians such as Josiah C. Russell (1958) have suggested a total European population loss of 50 to 60 per cent between 541 and 700. After the year 750, major epidemic diseases did not appear again in Europe until the Black Death of the 14th century. The disease Smallpox, which was eradicated in the late 20th century, did not definitively enter Western Europe until about 581 when Bishop Gregory of Tours provided an eyewitness account that describes the characteristic findings of smallpox. Waves of epidemics wiped out large rural populations. Most of the details about the epidemics are lost, probably due to the scarcity of surviving written records.