The Silk Road's high-altitude trade routes would have been impossible without yaks.

Domesticated yaks (Bos grunniens) possess unique physiological adaptations that allow them to survive at altitudes up to 20,000 feet. Unlike other bovines, yaks have larger lungs and a heart that is disproportionately large relative to their body size. This anatomical advantage allows them to process limited oxygen much more efficiently than horses or cattle. Their blood also contains a higher concentration of red blood cells and a unique type of hemoglobin that binds oxygen more effectively in thin air.Historical records from the Han Dynasty indicate that yak caravans were already established by the 2nd century BCE to navigate the treacherous 'Tea Horse Road.' These routes connected the high-altitude Tibetan Plateau with the lowlands of Yunnan and Sichuan. While a horse might require 10 to 15 pounds of grain daily, a yak can survive by grazing on sparse alpine grasses and mosses. This self-sufficiency made long-distance trade economically viable across thousands of miles of barren terrain.Modern genetic studies conducted by the Chinese Academy of Sciences suggest that yaks were domesticated approximately 7,300 years ago. This domestication was a turning point for human migration into the high-altitude regions of Central Asia. Without the yak's ability to carry 15% to 20% of its body weight over 15 miles a day in sub-zero temperatures, the cultural and economic exchange between ancient India and China would have been severely restricted. Today, an estimated 14 million yaks continue to support the livelihoods of pastoralists across the Hindu Kush and Himalayan ranges.