Yan tan tethera

Yan Tan Tethera or yan-tan-tethera is a sheep-counting system traditionally used by shepherds in Yorkshire, Northern England and some other parts of Britain. The words may be derived from numbers in Brythonic Celtic languages such as Cumbric which had died out in most of Northern England by the sixth century, but they were commonly used for sheep counting and counting stitches in knitting until the Industrial Revolution, especially in the fells of the Lake District. Though most of these number systems fell out of use by the turn of the 20th century, some are still in use.