The Hijra (Migration)
By the order of Allah Almighty, Hazrat Muhammad (PBUH) migrates to Medina as it was the last hope of survival of Hazrat Muhammad and his followers this migration from Mecca to Medina is known as the Hijra. And from this event of migration Hijri Calendar was established and started. This called as Islamic Calendar or Lunar Calendar.
Spreading the message of Islam.
After the migration to Medina, in the city of Medina, the Holy Prophet Muhammad (PBUH) carried on preaching of the new religion Islam. Revelations were continuing here and the religion was ever expanding the Quraish and Meccans did not discontinue the enmity with Muslims living even in Medina. There Major wars happened between them and then after a long time of almost nine years Meccans surrendered in front of Muslims. The Command of the Muslims was in the hand of the Hazrat Muhammad, The Holy Prophet. At the time of conquer of the Mecca, the believers destroyed all idols and spread their belief in on God.
Ascension of the Prophet at one Night
One night of 27th Rajab of the 10th year of messenger hood, the archangel Gabriel took Hazrat Muhammad on a journey to the skies and heavenly steed Buraq and first went to the Al Asqa Mosque in Jerusalem and there he (PBUH) offered prayer along with other prophets, Moses Abraham, Jesus, Noah, Adam etc. After offering the prayer he ascended to the skies, paradise and Hell and lastly he (PBUH) met face to face with the God. Then He (PBUH) returned to earth for spreading the eternal message of Islam. As per the Islamic beliefs, the only person is Hazrat Muhammad who saw Heaven and Hall while being alive.
Spreading of Divine religion after Muhammad Hazrat Muhammad left this world in 632 AD. After Hazrat Muhammad the work of spreading the religion Islam is continuing up till now . As this religion is a complete code of life and encompasses the all friends the all friends of life the human beings.