Maymuna bint Al-Harith married the Prophet (PBUH) in the year 7 AH shortly after the Muslims had been allowed to perform Umrah under the terms of the Treaty of Hudaybiyyah. Her name was originally Barra but after her marriage to the Prophet (PBUH), he changed her name to Maymuna, Arabic for "blessed".
Her sisters were Izza, Asma and Lubaba. She was also half-sister to Zaynab bint Khuzayma. She was at the age of 36 and the Prophet 60 when the marriage took place.
"It is not lawful for you (O Muhammad, to marry more women after this..." (Quran 33:52)