I asked a muslim co-worker about this yesterday. ALthough in recent years it has spilled over elsewhere in the Muslim world, it is predominately an arabic practice. Arabs are in Saudi Arabia, Jordan, Egypt, Lebanon, Iraq, Lybia, Syria, etc. With the exception of SA, where no other religion is allowed, the others have substantial minorities of Arab Christians, and before Muhammad's rise to power in what is now SA, Christianity was one of the major religions. But religion is not the relevant factor as much as arabic culture. Honor killing as it is known in the arab middle east doesn't happen in Bosnia, Iran, Turkey, Indonesia, Pakistan. So its an ethnic/cultural thing..