This was the first Islamic empire, based off a claim that they descended from Muhammed. They had a decentralized government and took influence from the Persians and Byzantine governments. It also absorbed culture from Greece and China, at the same time creating their own. Arabic became the language. Through trade, Islam spread to North Africa and Spain, where Abd Al Rahman united the religions under one rule. Baghdad became a learning center and vibrant capital. New foods, a green revolution, helped expand the population. This empire basically replaced the Roman empire.