The ninth year of hijrah is known as the "Year of Deputation." This is because during this year, many delegations from different tribes and regions came to the Prophet Muhammad (peace be upon him) in Medina to declare their acceptance of Islam and to seek his guidance. These delegations included both Arabs and non-Arabs, and their conversions helped to spread Islam throughout the Arabian Peninsula. The Year of Deputation was a significant year in the history of Islam, as it marked the growing acceptance of the new religion among the people of Arabia.