The Indian subcontinent was effectively united (excluding modern-day Tamil Nadu and parts of Kerala) under the Mauryan Dynasty by Ashoka the Great in the third century BCE. Ashoka was a great military commander, but also a notable proponent of religious tolerance.

In the third century CE the Roman Empire experienced a series of disastrous civil wars that led the Emperor Diocletian to believe that the empire was too large for any one centralized government to administer. He divided the empire into a tetrarchy - four distinct, but united provinces. This division would lead to the formation of the Eastern Roman Empire and the Western Roman Empire.

The Eastern Roman Empire was created by the Emperor Constantine in 330 CE. The Byzantine Empire is another name for the Eastern Roman Empire, so it stands to reason that the capital was called Byzantium. The city of Byzantium has also been called Constantinople and, since the Ottoman conquest in 1453, Istanbul.

The Ptolemaic Kingdom was established in modern-day Egypt in 323 BCE. It was one of the Hellenistic kingdoms that arose from the division of the conquests of Alexander the Great. It was ruled by the Ptolemaic dynasty until the death of Queen Cleopatra in 30 BCE.

The Achaemenid Empire is sometimes also called the First Persian Empire, it was founded in 552 BCE by Cyrus the Great.

The Pax Romana is a period relative peace and prosperity within the Roman Empire. Most historians agree that the Pax Romana began in 27 BCE with the ascension of the Roman Emperor Augustus Caesar and ended with the death of Marcus Aurelius in 180 CE.

The Roman Empire is one of the largest land empires ever seen in human history, but it did not come cover any of these modern-day countries. The Roman Empire, for example, failed to conquer Scotland and instead constructed Hadrian’s Wall - as a barrier between England and Scotland - to keep out barbarians during their attempted conquest of Britain.

The Qin Dynasty emerged victorious from the Warring States Period of Chinese history. The dynasty was very short-lived (221 - 206 BCE), but due to the rule of Qin Shi Huangdi is one of the most influential dynasties in Chinese history. The dynasty was so short-lived, in part, due to its strict adherence to the unpopular and autocratic philosophy of legalism.

All of these regions were, at one point or another, territories of the Roman Republic. Greece was conquered reasonably early in the history of Rome. Iberia and Syria soon followed suit in the second and first centuries BCE. Gaul (modern-day France) was conquered by Julius Caesar in the first century BCE. All of these would also be territories of the Roman Empire.

One of the main reasons why the Roman empire collapsed was that it became too large to administer, which was a difficulty also faced by the Persian empire. Many historians say that Rome actually became a victim of its own success — as it continued to conquer new lands, it became too big to control. As for the other answer choices, differences between social classes were large and stratified. Religion actually served as a uniting force circa 300 CE when Constantine declared Christianity as the official religion of Rome. Lastly, Rome had very sound institutions such as a constitution, laws, and legislatures.