The introduction of the Muslim calendar
The leader of the believers, Umar bn Khattab [RA] introduced the Islamic calendar in the year 639,consisting of twelve lunar months. 622CE.
The outbreak of plague in Syria and Palestine
In 639, there was an outbreak of an infectious disease known as bubonic plague in Syria and Palestine which had very serious consequences. About 25,000 Muslims were said to have perished and many took refuge in the desert from the plague-Infected cities. Among the dead were the commander-in-chief and Syrian governor Abu Ubaidah al-Jarrah, and Yezid bn Abi Sufyan who had played a distinguished role as a column commander throughout the Syrian campaign. Umar [RA] himself visited Syria to reorganize the administration, which became badly disrupted following the death of so many prominent leaders. In place of Abu Ubaida, Umar appointed Muawiya, the eldest surviving son of Abu Sufyan and former secretary to the Prophet (peace and blessings be upon him), governor of Syria.
This article was culled from the publications of Deen Communication Limited