When Sages and Rishis in ancient times indulging in contemplation (chintan) realized there was more to life than physically visible, they tried developing their brain power, mind power. Indulging in positivity all the time these accomplished, highly evolved sages and Rishis finally realized that brainpower could be involved up to infinity and started highly evolved sessions of yoga.
Channelizing sexual energy they realized that something called kundalini that lay dormant in the base of spine could be activated and raised to the crown chakra. They also realized the dormant lying kundalini shakti was in the form of a serpent. It gradually rises up when we indulged in absolute celibacy (eradication of negative thoughts to our brain in totality).
By hit and trial method these evolved sages and Rishis finally accomplished the unachievable. Sages like Yajnavalkya raised their kundalini to the top resulting in opening of Sahasra Pushpa (thousand petalled Lotus) existing in our brain behind forehead. Yajnavalkya immediately reached state of enlightenment, kaivalya jnana forever.
In erstwhile Bharatvarsha (now India) hordes of sages and Rishis successfully raised their kundalini to the crown chakra. Every single Upanishad (independent spiritual treatise) is a treatise invoked by an enlightened one independent of others. Every single Upanishad had different spiritual message to convey.
The founders of kundalini are sages and Rishis of erstwhile Bharatvarsha (now India). In absence of origination of kundalini shakti, this vital cosmic energy would have remained dormant in base of spine forever. With evolution of brainpower came recognition of kundalini energy, the most vital of all energies made available to mankind by God Almighty.
In absence of kundalini shakti none in this world could ever reach state of enlightenment.
Sage Yajnavalkya was spiritual mentor of King Janaka (father of Sita in Ramayana). As Ramayana precedes Mahabharata by about 1500 years, in all likelihood the concept of kundalini existed above 5000 years before now.