How the Nomads kept kefir going

I was reading that the early nomads, who had no way to refrigerate anything, let their kefir going, and what the article said was that when they milked their goat/camel/etc, they simply added that fresh milk into the bag where they carried their kefir, and as it went through the day, it became fermented kefir, too.
It was a continuous process, not something like we do now where, we start a batch each day either from grains or from culture starters.
Has anyone ever tried doing this ?
I am thinking about just leaving the kefir sit out on the counter as usual, but when I use a cup of it, then I will replace that with another cup of fresh milk, so it will always be in the culturing process.

Many people do consequent fermentation ‘‘back to back’’ nowadays also.
We recommend that as it reduces the initial cost of the starter and also because it is one of the ways to mix the kefir species with environmental ones, that can enhance it.

We really do not know how the people back in the days did it exactly, however although with no fridges they use dark and deep pits, and caves when possible. If in mountain rarely became too hot anyway

The perception of the time also was different. For them storing something in a bag for a week with no spoilage was a huge amount of time. With no fermenting the milk goes off in hours