Until the invention of steam ploughing in the 1850’s, the only source of energy for agriculture was human or animal muscle power. Oxen, sometimes cows, was more frequently used in the medieval period, but later more efficient heavy horses became available. The Watkins photographic collection in The Radnorshire Society Archive has a number of excellent photographs from the first half of the twentieth century of horses being used on the farm for ploughing, hay making and transport.