Ethiopia: It is mostly practiced among three tribes. The Amhara, Oromo, and Adere. The Muslim Oromo's and Adere perform this act because of its religious importance, while the Amhara's it’s a culture act. One of the reasons in the past for FGM (Female Genital Mutilation) was that virginity was a prerequisite for marriage (most marriages were arranged), and that it would discourage promiscuity after marriage.

Nowadays, there has been a decrease mainly due to awareness, but also females are free to marry anyone they wish. Also, I can't recall the date, but there was a campaign by the Muslim leaders advocating the less extensive Sunni circumcision.

Hope this helps..