These things, like many things in the Vedas, are related to codes. Indeed, many people try to look at the Sanskrit texts scientifically in an academic way, without realizing that the sages (Rishis) who wrote them were initiates of the highest caliber and training, and in other cases were Gods. That is, already in those days there was an understanding of the need to protect knowledge. The concept of Yugi is a classic example. Different interpretations give completely different ways of looking at these things.
According to the information written by the High Priestess Maxine, the course of one era in the understanding of Western astrology is 2160 years. This is the duration of one era (for example, the era of Pisces has ended at the moment). However, the Vedic view of these things rather describes the general state of decline (or ascension) of humanity, spiritual discipline on the planet and such things. In this sense, Satya Yuga is more like the Elin description of the Golden Age. It was followed by Bronze, then Iron (which we are in), and then Gold again. This is a more similar concept. Each period ended with an obvious “watershed” of civilization into before and after. The last time this happened was with the decline of antiquity. So we can conditionally say that Kali Yuga, in our understanding, began with the decline of antiquity.
