Have no ancient Indian people can answer this question, also do not know to have made modern concrete textual research.
it is said that the indians are the earliest practice yoga does not use yoga MATS, they act day night, in the most simple places, to body and mind, and the communication of the universe. However, modern people practicing yoga has totally different from the ancient indians. Yoga mat became the indispensable adjunct. Because yoga mat made of special materials, different from general mat or carpet, can rise to prevent slippery, prevent touch in areas such as the spine, hip, knee and ankle injuries. There is a kind of comparison is one thing: yoga mat can play a role of insulation, prevent gathered when practicing the body's energy was taken to enrage.