By around 1000 BC, the steppes of Central Asia were home to nomadic, horse-based cultures such as the Scythians, the Huns - who under their ruler Attila threatened the Roman Empire in the fifth century AD - and the Mongols, who rose to prominence in the 13th century. It was as a defence against these fast-moving nomads that the Chinese built the Great Wall. Central Asia was also the setting for important trade routes linking east and west, such as the famous Silk Road.
