Over the last millennium, Nowruz has developed and expanded, incorporating new social, religious and cultural influences as it spread along the Silk Roads. Its date, originally calculated according to ancient astronomical practices, was revised and recalculated on numerous occasions in the 11th and 12th centuries as Nowruz continued to be a celebration of great social significance under various rulers and regimes. Renowned scholars, such as Abu Rayhan al-Bīrūnī (973-1048), Mahmud Kashgari (1005-1102), and Omar Khayyam (1048-1131) are among the many intellectuals who studied the date of Nowruz.
