Female Genital Mutilation (FGM) is an invasive and painful surgical procedure that is usually performed without anesthetic on girls before puberty. There are about 100 to 140 million women who have been circumcised. An average of about four girls a minute continue to be mutilated. Their clitoris is partially or completely removed. This inhibits or terminates sexual feelings. It has been a social custom in Northern Africa for many centuries.
Many people link FGM with the religion of Islam. Actually, it is a social custom that is practiced by Animists, Christians, and Muslims in those countries where FGM is common. There are many Muslim countries in which the mutilation is unknown.
FGM is occasionally performed in North America on girls of families have immigrated from countries where FGM is common. An analogous practice, Intersexual Genital Mutilation, (IGM) is sometimes performed on intersexual infants born with ambiguous genitalia.
As noted above, FGM is a social custom, not a religious practice. However, in those Muslim countries where it is practice, FGM is often justified by two controversial sayings of the Prophet Mohammed that seem to favor sunna circumcision. The authenticity of these sayings are unconfirmed, and some scholars have refuted them. Even if true, they only permit the practice; they do not mandate it.
FGM has probably been performed for at least 1,400 years (some references estimate 2,000 years), and started during what Muslims call "al-gahiliyyah" (the era of ignorance). The Qu'r'an, Hebrew Scriptures (Old Testament) and Christian Scriptures (New Testament) is silent on the subject. The Sunnah (the words and actions of the Prophet Mohammed) contain a number of references to female circumcision:
http://www.religioustolerance.org/fem_cirm.htm