The idea of celebrating Teachers' Day took ground in many countries during the 20th century; in most cases, they celebrate a local educator or an important milestone in education (for example, Argentina commemorates Domingo Faustino Sarmiento's death on September 11 since 1915, while India celebrates Dr. Sarvepalli Radhakrishnan's birthday on September 5 since 1962). This is the primary reason why countries celebrate this day on different dates, unlike many other International Days.