The Inca ruled over a vast swathe of land on the Pacific coast of South America before the arrival of the Spanish in the sixteenth century. The Inca practiced terrace farming and constructed an elaborate road network stretching for thousands of miles along the coast and through the Andean foothills. They are also well-known for their extremely stratified and hierarchical society. However, they did not possess a system of writing. Instead they employed the knot-tying system known as quipu.

The Mayan civilization emerged in Mesoamerica during the classical period of American history. They are renowned for their art and architecture and their mastery, for the time period, of astronomy and the motion of celestial objects. The decline of the Mayan civilization began in the ninth century C.E., but it is not known what exactly caused the downfall. The Mayan people continued to live in small communities until eventually eradicated or assimilated during the Spanish conquest of Latin America.

The Tang dynasty, which ruled from 618 - 906 CE, was the most powerful Chinese dynasty of the classical period. The Tang ruled over the largest stretch of the land of all these dynasties; including parts of Central Asia, Tibet, Manchuria, and southeast Asia.

After the division of the Mongol Empire, Kublai Khan ruled over the largest stretch of territory. He controlled Karakorum and the Mongol homeland, the entirety of China and Korea, parts of southeast Asia, Tibet, and parts of Central Asia.

The Mamluk Sultanate was founded in Egypt in the thirteenth century. It began with the overthrow of the Abbasid Caliphate. The Mamluks ruled over most of Egypt and the Levant for a few centuries before being conquered by the growing Ottoman Empire in the sixteenth century.

In 1398, the Central Asian Mongol-Turkic warlord Timur invaded the Delhi Sultanate and sacked the city of Delhi. This contributed greatly to the weakening of the Delhi Sultanate, which would never again rule with the same authority. The Sultanate would come to an end in the early sixteenth century when it was conquered by the Mughals.

The Toltec civilization emerged in pre-Columbian Mexico in the 800s CE. They were a warrior society and grew wealthy and powerful on the back of military conquest. They were not contemporaries of the Olmecs (who preceded them by more than a thousand years), but they were contemporaries of the Aztecs.

Osman I founded the Ottoman Empire at the very end of the thirteenth century and, although it was only a minor emirate during his lifetime, it soon grew to control most of the Middle East and a large portion of southeastern Europe.

All of these statements are correct except that the Mongol territory was divided into two great empires. It was, in fact, divided into four great empires — the Empire of Kublai Khan, which ruled over China and the Mongol homeland; the Jagatai Empire, which ruled over Samarkand and Central Asia; the Golden Horde, which ruled over Russia and parts of Eastern Europe; and the Ilkhan Empire, which ruled over parts of the Middle East and Persia.

It is essentially impossible to define the world’s largest empire – the historical definition of “large” can have various meanings, from population size to geographic extent to level of political control and/or societal consolidation. However, it is possible to determine the world’s largest continuous empire (aka side-by-side, with all territories in physical proximity to each other). This honor belongs to the Mongol Empire, first created under the infamous auspices of Genghis Khan. Beginning with Genghis Khan’s assumption of leadership in 1206, the Mongol Empire continually expanded its borders through warfare, eventually stretching all the way across Eastern Europe to the Sea of Japan and southward across the Indian subcontinent and into modern-day Iran.