Dawah, Islamic missionary work, means to "invite" (in Arabic, literally "calling") to
Islam, which is estimated to be the second-largest religion, after
Christianity. After the death of the
Islamic prophet Muhammad, from the 7th century onwards, Islam spread rapidly from the
Arabian Peninsula to the rest of the world through either trade and exploration or
Muslim conquests. The purpose of
Islamic missionary activity is to grow the
Muslim ummah.