An advance on the basic design was the iron ploughshare, a replaceable horizontal cutting surface mounted on the tip of the share. The earliest ploughs with a detachable and replaceable share date from around 1000 BC in the Ancient Near East, and the earliest iron ploughshares from about 500 BC in China. Early mould boards were wedges that sat inside the cut formed by the coulter, turning over the soil to the side. The ploughshare spread the cut horizontally below the surface, so that when the mould board lifted it, a wider area of soil was turned over. Mould boards are known in Britain from the late 6th century onwards.