Ancient Rome was an Italic civilization that began on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to become one of the largest empires in the ancient world with an estimated 50 to 90 million inhabitants (roughly 20% of the world's population) and covering 6.5 million square kilometers (2.5 million sq mi) at its height between the first and second centuries AD.