Complex sentence: This is probably what inspired the later Saxon inhabitants of the area to name it after their god Grim (more commonly known as Odin); the shafts were not investigated however and their purpose not understood until the nineteenth century.
Split into simpler sentences: This is probably what inspired the later Saxon inhabitants of the area to name it after their god Grim (more commonly known as Odin). The shafts were not investigated, however and their purpose not understood, until the nineteenth century.