Brāhmī is generally believed to be derived from a Semitic script such as the Imperial Aramaic alphabet, as was clearly the case for the contemporary Kharosthi alphabet that arose in a part of northwest Indian under the control of the Achaemenid Empire. Rhys Davids suggests that writing may have been introduced to India from the Middle East by traders. Another possibility is with the Achaemenid conquest in the late 6th century BCE. It was often assumed that it was a planned invention under Ashoka as a prerequisite for his edicts. Compare the much better-documented parallel of the Hangul script.