Medina also officially transliterated as Madinah on Saudi maps and in modern Islamic literature generally, is a modern city in the Hejaz region of western Saudi Arabia, and serves as the capital of Al Madinah Province. An alternative name is Madinat Al-Nabi ("The City of the Prophet," i.e. Muhammad). The Arabic word madinah simply means "city." Before the advent of Islam, the city was known as Yathrib but was personally renamed by Muhammad.
It is the second holiest city in Islam after Mecca and the burial place of the Islamic Prophet Muhammad. Medina is critically significant in Islamic History for being where Muhammad's final religious base was established after the Hijrah and where he died in 632 AD/11 AH. Medina was the power base of Islam in its first century, being where the early Muslim community (ummah) developed under the Prophet's leadership, then under the leadership of the first four caliphs of Islam: Abu Bakr, Omar, Othman and Ali.
In fact, Year 1 of the Islamic calendar is based on the year of the emigration of Muhammad and his original followers (Muhajirun) from Mecca to the city of Medina in 622 AD/1 AH.
Medina is home to the three oldest mosques in Islam, namely Al-Masjid an-Nabawi (The Prophet's Mosque), Masjid Quba' or Quba Mosque (the first mosque in Islam's history), and Masjid al-Qiblatain (The Mosque of the Two Qiblahs - the mosque where the direction of Muslim prayer, or qiblah, was switched from Jerusalem to Mecca).
Similarly to Mecca, entrance to the sacred core of Medina (but not the entire city) is restricted to Muslims only; non-Muslims are permitted neither to enter nor cross through the city center.
Muslims believe that the final chapters (surahs) of the Qur'an chronologically were revealed to the Prophet in Medina and are called Medinan surahs in contrast to earlier Meccan surahs