The riders of early domesticated horses probably used some type of bitless headgear made of sinew, leather, or rope. Components of the earliest headgear may be difficult to determine, as the materials would not have held up over time. For this reason, no one can say with certainty which came first, the bitted or the bitless bridle. There is evidence of the use of bits, located in two sites of the Botai culture in ancient Kazakhstan, dated about 3500–3000 BC. Nose rings appear on the equids portrayed on the Standard of Ur, circa 2600–2400 BC. To date, the earliest known artistic evidence of use of some form of bitless bridle comes in illustrations of Synian horseman, dated approximately 1400 BC.