As early as 3000 BC, people knew there was a need to direct rainwater, refuse, and sewage away from their buildings, as evident from the clay brick drains that have been found by archaeologists in the Indus Valley in South Asia. By 600 BC, the Romans were creating intricate road systems with drainage to keep them from flooding. These road systems were a major contributor to the success of the Roman Empire and they brought this technology all the way to Britain around 47 AD.