“Whenever the faeces is removed from the anal orifice by a stone, a clod or the like — although its becoming pure is a matter of consideration, praying like that is not objected and things that come into contact with the area do not become najis. The small particles and the viscidity that remain in the area are no problem either. It is not necessary to clean the anal orifice with three stones or three pieces of cloth but it is enough to do so using different corners/parts of a single stone or piece of cloth. Moreover, if the faeces is removed by wiping with the mentioned things only once, it suffices.” — Ayatollah Khomeini, courtesy of the Comparative Fatwas of the Supreme Leader, Ayatollah Khamenei, http://www.leader.ir/tree/index.php?catid=47
And Allah knows best.
If that’s not proof they’re still living in the stone age, I don’t know what is.