Complex sentence: While Pryderi rules Dyfed in south Wales, Gwynedd in north Wales is ruled by Math, son of Mathonwy, whose feet must be held by a virgin at all times except while he is at war.
Split into simpler sentences: While Pryderi rules Dyfed in south Wales, Gwynedd in north Wales is ruled by Math, son of Mathonwy. His feet must be held by a virgin at all times except while he is at war.