Empires: an overview

In the two thousand years after the first empires of Mesopotamia, one empire after another rose in West Asia and around the Mediterranean Sea. By the sixth century BCE the Iranians controlled most of the old Assyrian empire, and trade routes ran overland and along the coasts. In Greece, city-states such as Athens and Sparta were the centres of civic life.

Alexander, ruler of Macedon, conquered parts of North Africa, West Asia and Iran in the late fourth century BCE, reaching the river Beas, where his soldiers refused to go further. His empire broke up soon after his death, but Greek ideas and the Greek language spread across the region, which became 'Hellenised' (the Greeks called themselves Hellenes). Iranian culture remained at least as important.

Rome was at first a small but well-organised republic in central Italy. Taking advantage of the quarrels after Alexander, it took control of North Africa and the eastern Mediterranean from the second century BCE. Under Julius Caesar, a high-born general, Roman power reached present-day Britain and Germany in the middle of the first century BCE. Latin was the main language, while many in the east kept using Greek.

How the story continues:

• The empire became largely Christian after the emperor Constantine became a Christian in the fourth century CE.
• To make government easier it was split into eastern and western halves.
• In the west, arrangements with the frontier tribes (Goths, Visigoths, Vandals and others) broke down, and the western empire collapsed by the fifth century CE. The tribes set up their own kingdoms.
• The eastern empire, centred on Constantinople, lasted much longer, but between the seventh and fifteenth centuries most of its lands were taken by the Arab empire founded by the followers of the Prophet Muhammad, and its successors.
• Pastoral peoples from the north, including Turkic tribes, often attacked and took over the region's cities. The last to try were the Mongols under Genghis Khan and his successors in the thirteenth century.

What drove these empires? All of them sought to control the rich trading networks of the region and its links with India and China. They built systems of government to keep trade stable, and each often took over the achievements of the one before. Over time Persian, Greek, Latin and Arabic became the region's great written languages.

These empires were not very stable, partly because of quarrels over resources and partly because of tense relations with the pastoral peoples to the north, on whom they depended for trade, labour and soldiers. Not every empire was centred on cities: the Mongol empire was run by pastoral people, successfully, for a long time. Religions that appealed across many ethnic groups and languages, such as Christianity (from Palestine, first century CE) and Islam (seventh century CE), helped hold large empires together.