There is no actual way that "postural" yoga is 5,000 years old. The first mentions of yoga in the ṛgveda, which your link suggests have literally nothing to do with stretching or being spiritual but everything to do with the economy and culture of the early ṛgvedic period, which spun on the binary of "yoga" (martial action) and "kṣema" (rest). That is, the period of time defined as "yoga" began at the moment the men joined to then go off and fight and the it ended after battle (and the booty of new slaves and cows) had occurred. See https://psdmccartney.medium.com/the-language-of-yoga-e71d736836b5 as one example.